The Platform for Privacy Preferences 1.0 (P3P1.0) Specification

W3C Working Draft 15 September 2000

This Version:

http://www.w3.org/TR/2000/WD-P3P-20000915

Latest Public Version:

http://www.w3.org/TR/P3P

Previous Version:

http://www.w3.org/TR/2000/WD-P3P-20000510

Editor:

Massimo Marchiori, W3C/MIT/UNIVE, (massimo@w3.org)

Authors:

Lorrie Cranor, AT&T

Marc Langheinrich, ETH Zurich

Massimo Marchiori, W3C/MIT/UNIVE

Martin Presler-Marshall, IBM

Joseph Reagle, W3C/MIT

Copyright ©2000 W3C^® (MIT, INRIA, Keio), All Rights Reserved. W3C liability, trademark, document use and software licensing rules apply.

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Abstract

This is the specification of the Platform for Privacy Preferences (P3P). This document, along with its normative references, includes all the specification necessary for the implementation of interoperable P3P applications.

Status of This Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. The latest status of this document series is maintained at the W3C.

This is the 15 September 2000 public W3C Working Draft of "The Platform for Privacy Preferences 1.0 (P3P1.0) Specification", for review by W3C members and other interested parties. This document has been produced by the P3P Specification Working Group as part of the P3P Activity.  It is a draft document and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use W3C Working Drafts as reference material or to cite them as other than "work in progress". A list of current public W3C Working Drafts can be found at http://www.w3.org/TR. A revised version of this specification is expected to advance toward W3C Recommendation status after two interoperable implementations have been demonstrated.

A change log with a summary of the modifications occurred from the previous public version is included at the end of this document for convenience.

Please send comments to www-p3p-public-comments@w3.org (publicly archived).

Table of Contents

1. Introduction
   1. The P3P1.0 Specification
      1. Goals and Capabilities of P3P 1.0
      2. Example of P3P in Use
      3. P3P Policies
      4. P3P User Agents
      5. Implementing P3P1.0 on Servers
      6. Future Versions of P3P
   2. About this Specification
   3. Terminology
2. Referencing Policies
   1. Overview and Purpose of Policy References
   2. Locating Policy Reference Files
      1. Well-Known Location
      2. HTTP Headers
      3. The HTML link Tag
   3. Policy Reference File Syntax and Semantics
      1. Example Policy Reference File
      2. Policy Reference File Definition
         1. Policy reference file processing
            1. Significance of order
            2. Wildcards in policy reference files
         2. The META and POLICY-REFERENCES elements
         3. Policy reference file lifetimes and the EXPIRY element
            1. Motivation and mechanism
            2. The EXPIRY element
            3. Use of HTTP headers
            4. Error handling for policy reference file lifetimes
         4. The POLICY-REF element
         5. The INCLUDE and EXCLUDE elements
         6. The EMBEDDED-INCLUDE and EMBEDDED-EXCLUDE elements
         7. The METHOD element
         8. The POLICIES element
      3. Forms and Related Mechanisms
   4. Additional Requirements
      1. Non-ambiguity
      2. Multiple Languages
      3. The Safe Zone
      4. Non-discrimination of Policies
      5. Security of Policy Transport
      6. Policy Updates
   5. Example Scenarios
3. Policy Syntax and Semantics
   1. Example policies
      1. English language policies
      2. XML encoding of policies
   2. Policies
      1. The POLICY element
      2. The ENTITY element
      3. The ACCESS element
      4. The DISPUTES element
      5. The REMEDIES element
   3. Statements
      1. The STATEMENT element
      2. The CONSEQUENCE element
      3. The PURPOSE element
      4. The RECIPIENT element
      5. The RETENTION element
      6. The DATA-GROUP and DATA elements
   4. Categories
   5. Extension Mechanism
   6. APPEL processing
4. Data Schemas
   1. The DATA-DEF and DATA-STRUCT elements
   2. Persistence of Dataschemas
   3. Basic Data Structures
      1. Dates
      2. Names
      3. Certificates
      4. Telephones
      5. Contact Information
         1. Postal
         2. Telecommunication
         3. Online
      6. Access Logs and Internet Addresses
         1. URI
         2. ipaddr
         3. Access Log Information
         4. Other HTTP Protocol Information
   4. The Base Data Schema
      1. User Data
      2. Third Party Data
      3. Business Data
      4. Dynamic Data
   5. Categories and Data Elements/Structures
      1. Fixed-Category Data Elements/Structures
      2. Variable-Category Data Elements/Structures
   6. Using Data Elements
5. Appendices
   Appendix 1: References (Normative)
   Appendix 2: References (Non-normative)
   Appendix 3: The P3P Base Data Schema Definition (Normative)
   Appendix 4: XML Schema Definition (Normative)
   Appendix 5: XML DTD Definition (Normative)
   Appendix 6: ABNF Notation (Non-normative)
   Appendix 7: P3P Guiding Principles (Non-normative)
   Appendix 8: Working Group Contributors (Non-normative)

1. Introduction

The Platform for Privacy Preferences Project (P3P) enables Web sites to express their privacy practices in a standard format that can be retrieved automatically and interpreted easily by user agents. P3P user agents will allow users to be informed of site practices (in both machine- and human-readable formats) and to automate decision-making based on these practices when appropriate. Thus users need not read the privacy policies at every site they visit.

Although P3P provides a technical mechanism for ensuring that users can be informed about privacy policies before they release personal information, it does not provide a technical mechanism for making sure sites act according to their policies. Products implementing this specification MAY provide some assistance in that regard, but that is up to specific implementations and outside the scope of this specification. However, P3P is complementary to laws and self-regulatory programs that can provide enforcement mechanisms. In addition, P3P does not include mechanisms for transferring data or for securing personal data in transit or storage. P3P may be built into tools designed to facilitate data transfer. These tools should include appropriate security safeguards.

1.1 The P3P1.0 Specification

The P3P1.0 specification defines the syntax and semantics of P3P privacy policies, and the mechanisms for associating policies with Web resources. P3P policies consist of statements made using the P3P vocabulary for expressing privacy practices. P3P policies also reference elements of the P3P base data schema -- a standard set of data elements that all P3P user agents should be aware of. The P3P specification includes a mechanism for defining new data elements and data sets, and a simple mechanism that allows for extensions to the P3P vocabulary.

1.1.1 Goals and Capabilities of P3P 1.0

P3P version 1.0 is a protocol designed to inform Web users of the data-collection practices of Web sites. It provides a way for a Web site to encode its data-collection and data-use practices in a machine-readable XML format known as a P3P policy. The P3P specification defines:

• A standard schema for data a Web site may wish to collect, known as the "P3P base data schema"
• A standard set of uses, recipients, data categories, and other privacy disclosures
• An XML format for expressing a privacy policy
• A means of associating privacy policies with Web pages or sites
• A mechanism for transporting P3P policies over HTTP

The goal of P3P version 1.0 is twofold. First, it allows Web sites to present their data-collection practices in a standardized, machine-readable, easy-to-locate manner. Second, it enables Web users to understand what data will be collected by sites they visit, how that data will be used, and what data/uses they may "opt-out" of or "opt-in" to.

1.1.2 Example of P3P in Use

As an introduction to P3P, let us consider one common scenario that makes use of P3P. Sheila has decided to check out a store called CatalogExample, located at http://www.catalog.example.com/. Let us assume that CatalogExample has placed P3P policies on all their pages, and that Sheila is using a Web browser with P3P built in.

Sheila types the address for CatalogExample into her Web browser. Her browser is able to automatically fetch the P3P policy for that page. The policy states that the only data the site collects on its home page is the data found in standard HTTP access logs. Now Sheila's Web browser checks this policy against the preferences Sheila has given it. Is this policy acceptable to her, or should she be notified? Let's assume that Sheila has told her browser that this is acceptable. In this case, the homepage is displayed normally, with no pop-up messages appearing. Perhaps her browser displays a small icon somewhere along the edge of its window to tell her that a privacy policy was given by the site, and that it matched her preferences.

Next, Sheila clicks on a link to the site's online catalog. The catalog section of the site has some more complex software behind it. This software uses cookies to implement a "shopping cart" feature. Since more information is being gathered in this section of the web site, the Web server provides a seperate P3P policy to cover this section of the site. Again, let's assume that this policy matches Sheila's preferences, so she gets no pop-up messages. Sheila continues and selects a few items she wishes to purchase. Then she proceeds to the checkout page.

The checkout page of CatalogExample requires some additional information: Sheila's name, address, credit card number, and telephone number. Another P3P policy is available that describes the data that is collected here and states that her data will be used only for completing the current transaction, her order.

Sheila's browser examines this P3P policy. Imagine that Sheila has told her browser that she wants to be warned whenever a site asks for her telephone number. In this case, the browser will pop up a message saying that this Web site is asking for her telephone number, and explaining the contents of the P3P statement. Sheila can then decide if this is acceptable to her. If it is acceptable, she can continue with her order; otherwise she can cancel the transaction.

Alternatively, Sheila could have told her browser that she wanted to be warned only if a site is asking for her telephone number and was going to give it to third parties and/or use it for uses other than completing the current transaction. In that case, she would have received no prompts from her browser at all, and she could proceed with completing her order.

Note that this scenario describes one hypothetical implementation of P3P. Other types of user interfaces are also possible.

1.1.3 P3P Policies

P3P policies use an XML encoding of the P3P vocabulary to identify the legal entity making the representation of privacy practices in a policy, enumerate the types of data or data elements collected, and explain how the data will be used. In addition, policies identify the data recipients, and make a variety of other disclosures including information about dispute resolution, and the address of a site's human-readable privacy policy. P3P policies must cover all relevant data elements and practices (but note that legal issues regarding law enforcement demands for information are not addressed by this specification; it is possible that a site that otherwise abides by its policy of not redistributing data to others may be required to do so by force of law). P3P declarations are positive, meaning that sites state what they do, rather than what they do not do. The P3P vocabulary is designed to be descriptive of a site's practices rather than simply an indicator of compliance with a particular law or code of conduct. However, user agents may be developed that can test whether a site's practices are compliant with a law or code.

P3P policies represent the practices of the site. Intermediaries such as telecommunication providers, Internet service providers, proxies and others may be privy to the exchange of data between a site and a user, but their practices may not be governed by the site's policies.

1.1.4 P3P User Agents

P3P1.0 user agents can be built into web browsers, browser plug-ins, or proxy servers. They can also be implemented as Java applets or JavaScript; or built into electronic wallets, automatic form-fillers, or other user data management tools. P3P user agents look for P3P headers in HTTP responses and in P3P link tags embedded in HTML content. These special headers and tags indicate the location of a relevant P3P policy. User agents can fetch the policy from the indicated location, parse it, and display symbols, play sounds, or generate user prompts that reflect a site's P3P privacy practices. They can also compare P3P policies with privacy preferences set by the user and take appropriate actions. P3P can perform a sort of "gate keeper" function for data transfer mechanisms such as electronic wallets and automatic form fillers. A P3P user agent integrated into one of these mechanisms would retrieve P3P policies, compare them with user's preferences, and authorize the release of data only if a) the policy is consistent with the user's preferences and b) the requested data transfer is consistent with the policy. If one of these conditions is not met, the user might be informed of the discrepancy and given an opportunity to authorize the data release themselves.

1.1.5 Implementing P3P1.0 on Servers

Web sites can implement P3P1.0 on their servers by translating their human-readable privacy policies into P3P syntax and then publishing the resulting files. Automated tools can assist site operators in performing this translation. P3P1.0 can be implemented on existing HTTP 1.1-compliant Web servers without requiring additional or upgraded software. Servers may publish their privacy policies at a well-known location, or they may reference their P3P policies in HTML content using a link tag. Alternatively, compatible servers may be configured to insert a P3P extension header into all HTTP responses that indicates the location of a site's P3P policy.

Web sites have some flexibility in how they use P3P: they can opt for one P3P policy for their entire site or they can designate different policies for different parts of their sites. A P3P policy MUST cover all data generated or exchanged as part of a site's HTTP interactions with visitors. In addition, some sites may wish to write policies that cover all data an entity collects, regardless of how the data is collected.

1.1.6 Future Versions of P3P

The P3P Specification Working Group removed significant sections from earlier drafts of the P3P1.0 specification in order to facilitate rapid implementation and deployment of a P3P first step. The group envisions the release of future versions of the P3P specification after P3P1.0 is deployed. This specification would likely include improvements based on feedback from implementation and deployment experience as well as four major components that were part of the original P3P vision but not included in P3P1.0:

• a mechanism to allow sites to offer a choice of P3P policies to visitors
• a mechanism to allow visitors (through their user agents) to explicitly agree to a P3P policy
• mechanisms to allow for non-repudiation of agreements between visitors and web sites
• a mechanism to allow user agents to transfer user data to services

1.2 About this Specification

This document, along with its normative references, includes all the specification necessary for the implementation of interoperable P3P applications.

The [ABNF] notation used in this specification is specified in RFC2234 and summarized in Appendix 7. However, note that such syntax is only a grammar representative of the XML syntax: all the syntactic flexibilities of XML are also implicitly included; e.g. whitespace rules, quoting using either single quote (') or double quote ("), character escaping, comments, case sensitivity, order of attributes. Note that while XML allows flexibility in the ordering of element attributes, it does not allow flexibility in the ordering of elements. XML elements MUST be given in the order represented by the document type definitions (DTDs).

In the sections that follow a number of XML elements are introduced. Each element is given in angle brackets ("<element>"), followed by a list of valid attributes. All listed attributes are optional, except when tagged as mandatory. Note that many XML elements are shown in the BNF with separate beginning and ending tags to allow optional elements inside them. If no elements are included, then, following standard XML rules, a self-closing element may be used instead.

The following key words are used throughout the document and should be read as interoperability requirements. This specification uses words as defined in RFC2119 [KEY] for defining the significance of each particular requirement. These words are:

MUST or MUST NOT

This word or the adjective "required" means that the item is an absolute requirement of the specification.

SHOULD or SHOULD NOT

This word or the adjective "recommended" means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighed before choosing a different course.

MAY

This word or the adjective "optional" means that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product, for example; another vendor may omit the same item.

1.3 Terminology

Character

Strings consist of a sequence of zero or more characters, where a character is defined as in the XML Recommendation [XML]. A single character in P3P thus corresponds to a single Unicode abstract character with a single corresponding Unicode scalar value (see [UNICODE]).

Data Element

An individual data entity, such as last name or telephone number. For interoperability, P3P1.0 specifies a base set of data elements.

Data Category

A significant attribute of a data element or data set that may be used by a trust engine to determine what type of element is under discussion, such as physical contact information. P3P1.0 specifies base data categories.

Data Set

A known grouping of data elements, such as "user.home.postal". P3P1.0 specifies a number of base data schemas.

Equable Practice

A practice that is very similar to another in that the purpose and recipients are the same or more constrained than the original, and the other disclosures are not substantially different. For example, two sites with otherwise similar practices that follow different -- but similar -- sets of industry guidelines.

Personally Identifiable Data

Any information relating to an identified or identifiable individual.

Policy

A collection of one or more privacy statements together with information asserting the identity, URI, assurances, and dispute resolution procedures of the service covered by the policy.

Practice

The set of disclosures regarding data usage, including purpose, recipients, and other disclosures.

Preference

A rule, or set of rules, that determines what action(s) a user agent will take. A preference might be expressed as a formally defined computable statement (e.g., the [APPEL] preference exchange language).

Purpose

The reason(s) for data collection and use.

Repository

A mechanism for storing user information under the control of the user agent.

Safe Zone

Part of a Web site where the service provider performs only minimal data collection, and any data that is collected is used only in non-identifiable ways.

Service

A program that issues policies and (possibly) data requests. By this definition, a service may be a server (site), a local application, a piece of locally active code, such as an ActiveX control or Java applet, or even another user agent.

Service Provider (Data Controller, Legal Entity)

The person or legal entity which offers information, products or services from a Web site, collects information, and is responsible for the representations made in a practice statement.

Statement

A P3P statement is a set of privacy practice disclosures relevant to a collection of data elements.

URI

A Uniform Resource Identifier used to identify Web resources. For definitive information on URI syntax and semantics, see [URI]. URIs that appear within XML or HTML have to be treated as specified in [CHARMODEL], section Character Encoding in URI References. This does not apply to URIs appearing in HTTP header fields; the URIs there should always be fully escaped.

User

An individual (or group of individuals acting as a single entity) on whose behalf a service is accessed and for which personal data exists.

User Agent

A program whose purpose is to mediate interactions with services on behalf of the user under the user's preferences. A user may have more than one user agent, and agents need not reside on the user's desktop, but any agent must be controlled by and act on behalf of only the user. The trust relationship between a user and her agent may be governed by constraints outside of P3P. For instance, an agent may be trusted as a part of the user's operating system or Web client, or as a part of the terms and conditions of an ISP or privacy proxy.

2. Referencing Policies

2.1 Overview and Purpose of Policy References

Locating a P3P policy is one of the first steps in the operation of the P3P protocol. Services use policy references to state what policy applies to a specific URI or set of URIs. User agents use policy references to locate the privacy policy that applies to a page, so that they can process that policy for the benefit of their user.

Policy references are used extensively as a performance optimization. P3P policies are typically several kilobytes of data, while a URI that references a privacy policy is typically less than 100 bytes. In addition to the bandwidth savings, policy references also reduce the need for computation: policies can be uniquely associated with URIs, so that a user agent need only parse and process a policy once rather than process it with every document to which the policy applies. Furthermore, by placing the information about relevant policies in a centralized location, Web site administration is simplified.

A policy reference file is used to associate P3P policies with certain regions of URI-space. The policy reference file is used to make any or all of the following statements:

• The URI where a P3P policy is found
• The URIs or regions of URI-space covered by this policy
• The URIs or regions of URI-space not covered by this policy
• The regions of URI-space for embedded content on other servers that are covered by this policy
• The access methods for which this policy is applicable
• The period of time for which these claims are considered to be valid

All of these statements are made in the body of the policy reference file. The last can also be made using HTTP expiration headers on the policy reference file. See section 2.3 for examples and explanations.

2.2 Locating Policy Reference Files

This section describes the mechanisms used to indicate the location of a policy reference file. Detailed syntax is also given for the supported mechanisms.

The location of the policy reference file can be indicated using one of three mechanisms. The policy reference file may be located in a predefined "well-known" location, or a document may indicate a policy reference file through an HTML LINK tag, or through an HTTP header. The policy reference file specifies the P3P policy that applies to that document, and possibly to other URIs as well. The policy reference file is an XML (see [XML]) file that can specify the policy for a single Web document, portions of a Web site, or for an entire site. The policy reference file may refer to one or more P3P policies; this allows for a single reference file to cover an entire site, even if different P3P policies apply to different portions of the site.

Note that if user agents support retrieving HTML content over HTTP, they MUST handle all three mechanisms listed above interchangeably; none of the mechanisms overrides the other. See also the requirements for non-ambiguity.

Note that policies are applied at the level of HTTP entities. An entity, retrieved by fetching a URI, has a P3P policy associated with it. A "page" from the user's perspective may be composed of multiple HTTP entities; each entity may have its own P3P policy associated with it. As a practical note, however, placing many different P3P policies on different entities on a single page may make rendering the page and informing the user of the relevant policies difficult for user agents. Additionally, services SHOULD attempt to craft their policy reference files such that a single policy reference file covers any given "page"; this will speed up the user's browsing experience.

For a user agent to process the policy that applies to a given entity, it must locate the policy reference file for that entity, fetch the policy reference file, parse the policy reference file, fetch any required P3P policies, and then parse the P3P policy or policies.

This document does not specify how P3P policies may be associated with documents retrieved by means other than HTTP. However, it does not preclude future development of mechanisms for associating P3P policies with documents retrieved over other protocols. Furthermore, additional methods of associating P3P policies with documents retrieved using HTTP may be developed in the future.

2.2.1 Well-Known Location

Web sites using P3P MAY choose to place a policy reference file in a "well-known" location. To do this, a policy reference file would be placed in the site's /w3c directory, under the name p3p.xml. Thus a user agent could request this policy reference file by using a GET request for the resource /w3c/p3p.xml.

Note that sites are not required to use this mechanism. Additionally, if a site chooses to use this mechanism, the policy reference file located in the well-known location is not required to cover the entire site. For example, sites where not all of the content is under the control of a single organization MAY choose not to use this mechanism, or MAY choose to post a policy reference file which covers only a limited portion of the site.

Use of the well-known location for a policy reference file does not preclude use of other mechanisms for specifying a policy reference file. Portions of the site MAY use any of the other supported mechanisms to specify a policy reference file, so long as the non-ambiguity requirements are met.

For example, imagine a shopping-mall Web site run by the MallExample company. On their Web site (mall.example.com), companies offering goods or services at the mall would get a company-specific subtree of the site, perhaps in the path /companies/company-name. The MallExample company may choose to put a policy reference file in the well-known location which covers all of their site except the /companies subtree. Then if the ShoeStoreExample company has some content in /companies/shoestoreexample, they could use one of the other mechanisms to indicate the location of a policy reference file covering their portion of the mall.example.com site.

One case where using the well-known location for policy reference files is expected to be particularly useful is in the case of a site which has divided its content across several hosts. For example, consider a site which uses a different logical host for all of its Web-based applications than for its static HTML content. The other mechanisms allowed for specifying the location of a policy reference file require that some URI on the host being accessed must be fetched to locate the policy reference file. However, the well-known location mechanism has no such requirement. Consider the example of an HTML form located on www.example.com. Imagine that the action URI on that form points to server cgi.example.com. The policy reference file that covers the form is unable to make any statements about the action URI that processes the form. However, the site administrator publishes a policy reference file at http://cgi.example.com/w3c/p3p.xml that covers the action URI, thus enabling a user agent to easily locate the P3P policy that applies to the action URI before submitting the form contents.

2.2.2 HTTP Headers

Any document retrieved by HTTP MAY point to a policy reference file through the use of a new response header, the P3P header ([P3P-HEADER]). If a site is using P3P headers, it SHOULD include this on responses for all appropriate request methods, including HEAD and OPTIONS requests.

The P3P header gives one or more comma-seperated directives. The syntax follows:

[1]	p3p-header	=	`P3P: ` p3p-header-field *(`,` p3p-header-field)
[2]	p3p-header-field	=	policy-ref-field | extension-field
[3]	policy-ref-field	=	`policyref="` URI `"`
[4]	extension-field	=	token [`=` (token | quoted-string) ]
Here, URI is defined as per RFC 2396 [URI], token and quoted-string are defined by [HTTP1.1].

In keeping with the rules for other HTTP headers, the P3P portion of this header may be written in any case.

The policyref directive gives a URI which specifies the location of the policy reference file which will state the P3P policy covering the document that pointed to the reference file, and possibly others as well. Note that fetching the URI given in the policyref directive MAY result in a 300-class HTTP return code (redirection); user agents MUST interpret those redirects with normal HTTP semantics. Services should note, of course, that use of redirects will increase the time required for user agents to find and interpret their policies. The policyref URI MUST NOT be used for any other purpose beyond identifying and referencing P3P policies.

User-agents which find unrecognized directives MUST ignore the unrecognized directives. This is to allow easier deployment of future versions of P3P.

Example 2.1:

1. Client makes a GET request.

GET /index.html HTTP/1.1
Host: catalog.example.com
Accept: */*
Accept-Language: de, en
User-Agent: WonderBrowser/5.2 (RT-11)

2. Server returns content and the P3P header pointing to the policy of the page.

HTTP/1.1 200 OK
P3P: policyref="http://catalog.example.com/P3P/PolicyReferences.xml"
Content-Type: text/html
Content-Length: 7413
Server: CC-Galaxy/1.3.18

2.2.3 The HTML link Tag

Servers MAY serve HTML content with embedded link tags that indicate the location of the relevant P3P policy reference file. This use of P3P does not require any change in the server behavior.

The link tag encodes the information that could be expressed using the P3P header. The link tag takes the following form:

[5]	p3p-link-tag	=	`<link rel="P3Pv1" href="` URI `">`
Here, URI is defined as per RFC 2396 [URI].

Any policy reference file referenced by an HTML link tag MUST only be used to specify policies for resources with the same URI prefix as the policy reference file itself (and for embedded content). For example, if an HTML link tag references a policy reference file at http://www.example.com/users/sheila/p3p.xml then that policy reference file may only specify policies for local files in the /users/sheila/ directory and its subdirectories. User agents MUST ignore any other policy references made in this file (except embedded references).

In order to illustrate with an example the use of the link tag, we consider the policy reference expressed in Example 2.1 using HTTP headers. That example can NOT be expressed equally well by including in the web page http://catalog.example.com/index.html the following piece of HTML:

<link rel="P3Pv1"
    href="http://catalog.example.com/P3P/PolicyReferences.xml">

This is wrong because /index.html is not a local file within the P3P/ directory. A correct example would be instead:

<link rel="P3Pv1"
    href="http://catalog.example.com/PolicyReferences.xml">

Finally, note that since the p3p-link-tag is embedded in an HTML document, its character encoding will be the same as that of the HTML document. In contrast to P3P policy and policy reference documents (see section 2.3 and section 3 below), the p3p-link-tag need not be encoded using [UTF-8].

2.3 Policy Reference File Syntax and Semantics

This section explains the contents of policy reference files in detail.

2.3.1 Example Policy Reference File

Consider the case of a Web site wishing to make the following statements:

1. P3P policy /P3P/Policy1.xml applies to the entire site, except the subtrees /catalog, /cgi-bin, and /servlet.
2. P3P policy /P3P/Policy2.xml applies to all documents in the /catalog directory (and its subdirectories).
3. P3P policy /P3P/Policy3.xml applies to all documents in the /cgi-bin and /servlet directories (and their subdirectories), except for /servlet/unknown.
4. No statement is made about what P3P policy applies to /servlet/unknown.
5. These statements are valid for 2 days.

These statements could be represented by the following piece of XML:

Example 2.2:

<META xmlns="http://www.w3.org/2000/09/15/P3Pv1">
 <POLICY-REFERENCES>
  <EXPIRY max-age="172800"/>

    <POLICY-REF about="/P3P/Policy1.xml">
      <INCLUDE>/*</INCLUDE>
      <EXCLUDE>/catalog/*</EXCLUDE>
      <EXCLUDE>/cgi-bin/*</EXCLUDE>
      <EXCLUDE>/servlet/*</EXCLUDE>
    </POLICY-REF>

    <POLICY-REF about="/P3P/Policy2.xml">
      <INCLUDE>/catalog/*</INCLUDE>
    </POLICY-REF>

    <POLICY-REF about="/P3P/Policy3.xml">
      <INCLUDE>/cgi-bin/*</INCLUDE>
      <INCLUDE>/servlet/*</INCLUDE>
      <EXCLUDE>/servlet/unknown</EXCLUDE>
    </POLICY-REF>

 </POLICY-REFERENCES>
</META>

This example includes a relative expiry time in the document. The expiry time could also be expressed through HTTP headers:

1. The origin server serving this page could return a Cache-Control: max-age=172800 header with this file, or
2. The origin server could generate an Expires header dated 2 days past the Date header in the response.

2.3.2 Policy Reference File Definition

This section defines the syntax and semantics of P3P policy reference files. All policies MUST be encoded using [UTF-8]. P3P servers MUST encode their policy references using this syntax. P3P user agents MUST be able to parse this syntax.

One significant point to make about the syntax of policy reference files is that the syntax defined here does not have an extension mechanism. The syntax for P3P policies has a powerful extension mechanism, but that mechanism is not supported for policy reference files.

2.3.2.1 Policy reference file processing

2.3.2.1.1 Significance of order

A policy reference file may contain multiple POLICY-REF elements. If it does contain more than one element, they MUST be processed by user agents in the order given in the file. When a user agent is attempting to determine what policy applies to a given URI, it MUST use the first POLICY-REF element in the policy reference file which applies to that URI.

2.3.2.1.2 Wildcards in policy reference files

Policy reference files make statements about what policy applies to a given URI. Policy reference files support a simple wildcard character to allow making statements about regions of URI-space. The character asterix ("*") is used to represent a sequence of 0 or more of any character. No other special characters (such are those found in regular expressions) are supported. Note that since the asterix is also a legal character in URIs ([URI]), some special conventions have to be followed when encoding such "extended URIs" in a policy reference file:

• URIs represented in policy-ref files MUST be properly escaped, as in [URI].
• P3P User-Agents MUST escape any characters which should be escaped, as according to [URI], before attempting to match a URI for a policy.
• P3P User-Agents MUST un-escape any escaped sequences which resolve to URI-legal characters, according to [URI], before attempting to match a URI for a policy, EXCEPT
• Literal '*'s in URIs MUST be escaped by P3P User-Agents before attempting to match a URI for a policy.
• User-agents MUST ignore any URI pattern that do not conform to [URI]

:The wildcard character MAY be used in the INCLUDE and EXCLUDE elements, as well as the EMBEDDED-INCLUDE and EMBEDDED-EXCLUDE elements.

2.3.2.2 The META and POLICY-REFERENCES elements

The META tag element contains a complete policy reference file. Exactly one POLICY-REFERENCES element MUST be in a policy reference file. Additionally, some other XML markup can follow the POLICY-REFERENCES element, although that markup MUST be ignored by any P3P1.0 user agent.

POLICY-REFERENCES

This element MAY contain one or more POLICY-REF (policy reference) elements. It MAY also contain one EXPIRY element (indicating their expiration time), and also some in-line policies.

[6]	prf	=	`<META xmlns="http://www.w3.org/2000/09/15/P3Pv1">` policyrefs PCDATA "</META>"
[7]	policyrefs	=	"<POLICY-REFERENCES>" [expiry] *policyref [policies] "</POLICY-REFERENCES>"
Here PCDATA is defined in [XML].

2.3.2.3 Policy reference file lifetimes and the EXPIRY element

2.3.2.3.1 Motivation and mechanism

It is desirable for servers to inform user agents how long they can use the claims made in a policy reference file. By enabling clients to cache the contents of a policy reference file, it reduces the time required to process the privacy policy associated with a Web page. This also reduces load on the network. In addition, clients that don't have a valid policy reference file for a URI will need to use "safe zone" practices for their requests. If clients have policy reference files which they know are still valid, then they can make more informed decisions on how to proceed.

The lifetime of a policy reference file tells user agents how long they can rely on the claims made in the reference file. For example, if a policy reference file has a lifetime of 3 days, then a user agent need not reload that file for 3 days, and can assume that the references made in that reference file are good for 3 days. All of the policy references made in a single policy reference file will receive the same lifetime. The only way to specify different lifetimes for P3P policies is to use separate policy reference files for each policy.

When picking a lifetime for policies and policy reference files, sites need to pick a lifetime which balances two competing concerns. One concern is that the lifetime ought to be long enough to allow user agents to receive significant benefits from caching. The other concern is that the site would like to be able to change their policy without waiting for an extremely long lifetime to expire. It it expected that lifetimes in the range of 1-7 days would be a reasonable balance between these two competing desires. Sites also need to remember the policy update requirements when updating their policies.

When a policy reference file has expired, the information in the policy reference file MUST NOT be used by a user-agent until that user-agent has successfully revalidated the policy reference file, or has fetched a new copy of the policy reference file.

As stated in section 2.3, there are two mechanisms for specifying the lifetime of policy reference files. Two different mechanisms are provided to give sites additional flexibility in deploying policy reference files. A policy reference file MAY contain an EXPIRY element, which gives the lifetime for the file. If there is no EXPIRY element in the policy reference file, then the HTTP cache control headers associated with the policy reference file give the lifetime of the policy reference file.

Note that while user agents are not obligated to refetch policy reference files or policy files that have not expired, they MAY choose to revalidate those files before their expiry period has passed, in order to reduce the need for using "safe zone" practices.

2.3.2.3.2 The EXPIRY element

The EXPIRY element can be used in a policy reference file and/or in a P3P policy to state how long the policy reference file (or policy) remains valid. The expiry is given as either an absolute expiry time, or a relative expiry time. An absolute expiry time is a time, given in GMT, until which the policy reference file (or policy) is valid. A relative expiry time gives a number of seconds for which the policy reference file (or policy) is valid. This expiry time is relative to the time the response was sent from the origin server (as stated by the Date: header in the response).

[8]	expiry	=	"<EXPIRY" (absdate|reldate) "/>"
[9]	absdate	=	`date="` HTTP-date `"`
[10]	reldate	=	`max-age="` delta-seconds `"`
Here, HTTP-date is defined in section 3.3.1 of [HTTP1.1], and delta-seconds is defined in section 3.3.2 of [HTTP1.1].

2.3.2.3.3 Use of HTTP headers

When a policy reference file contains no EXPIRY element, the HTTP headers served with the policy reference file determine its lifetime. However, user agents MUST NOT use heuristic expiration based on last-modified to compute a lifetime for the reference file. When using the HTTP headers to determine the lifetime of a policy reference file, user agents MUST compute that lifetime for the policy reference file based on Expires, Cache-Control, or Pragma headers served with the file if they are available. The semantics of these headers are defined by [HTTP]. If none of these headers is available, the lifetime MUST be set to 24 hours from the time the document was sent from the origin server. Origin servers SHOULD use either the EXPIRY element or one of the HTTP headers listed above to give an explicit lifetime for their policy reference files.

The possible presence of caches in the network and the heuristic expiration mechanism in HTTP considerably complicates lifetime considerations. Consider the case of policy reference files that have no explicit cache lifetime defined by the origin server (i.e., none of the headers listed above are included in the response). A network cache will, in all likelihood, compute a cache lifetime for the policy reference file based on its last-modified date; the resulting cache lifetime could be significantly longer that 24 hours. If a cache implements HTTP 1.0, then when a user agent then retrieves this policy reference file, the user agent has no way to know how long the reference file may have been in the cache. It would then be impossible for the user agent to determine if the reference file's lifetime has already expired, or when it will expire. HTTP 1.1 caches improve the situation somewhat, as the HTTP protocol states that HTTP 1.1-compliant caches MUST send an Age header when serving a request from their cache. However, even this is not sufficient; the cache could return a file with an age exceeding the 24-hour lifetime defined here, resulting in a useless policy reference file. To avoid these problems, user agents MUST insure that they load a fresh copy of the policy reference file when it is fetched. Thus, a user agent MUST include either a Pragma: no-cache or a Cache-Control: no-cache request-header when fetching a policy reference file. The former is suggested for compatibility with HTTP 1.0 caches.

Note that it is impossible for a client to accurately predict the amount of latency that may affect an HTTP request. Thus, if the policy reference file covering a request is going to expire soon, clients MAY wish to consider warning their users and/or revalidating the policy reference file before continuing with the request.

2.3.2.3.4 Error handling for policy reference file lifetimes

The following situations have their semantics specifically defined:

1. When a policy reference file contains an EXPIRY element, and it is served with one of the HTTP headers listed in the previous subsection 2.3.2.3.3, the EXPIRY header takes precedence for determining the lifetime of the policy reference file.
2. An absolute expiry date in the past renders the policy reference file stale. This covers a date in an Expires: HTTP header as well as one in an expires-date attribute of an EXPIRY element.
3. An invalid or malformed expiry date, whether relative or absolute, should be considered to be in the past. This would result in the policy reference file being stale.

2.3.2.4 The POLICY-REF element

A policy reference file may refer to multiple P3P policies, specifying information about each. The POLICY-REF element describes attributes of a single P3P policy. Elements within the POLICY-REF element give the location of the policy and specify the areas of URI-space that each policy covers.

POLICY-REF

contains information about a single P3P policy.

about (mandatory attribute)

URI of the P3P policy. If this is a relative URI, it is interpreted relative to the URI of the policy reference file. Note that this MAY be a reference to a policy included in this policy reference file. To do this, the policy URI is given by #policy-name, where policy-name is the value given on the name attribute of a policy in this policy reference file.

policy-ref

=

`<POLICY-REF about="` URI `">`
*include
*exclude
*embedded-include
*embedded-exclude
*method-element
`</POLICY-REF>`

2.3.2.5 The INCLUDE and EXCLUDE elements

Each INCLUDE or EXCLUDE element specifies one local URI or set of local URIs. A set of URIs is specified if the wildcard character '*' is used in the URI-pattern. These elements are used to specify the portion of the Web site that is covered by the policy referenced by the enclosing POLICY-REF element.

When INCLUDE (and optionally, EXCLUDE) elements are present in a POLICY-REF element, it means that the policy specified in the about attribute of the POLICY-REF element applies to all the URIs at the requested host corresponding to the local-URI(s) matched by any of the INCLUDEs, but not matched by an EXCLUDE element.

If a METHOD element (section 2.3.2.7) specifies one or more methods for an enclosing policy reference, it follows that all methods not mentioned are consequently not covered by this policy. In the case that this is the only policy reference for a given URI prefix, user agents MUST assume that NO policy is in effect for all methods NOT mentioned in the policy reference file.

It is legal, but pointless, to supply an EXCLUDE element without any INCLUDE elements; in that case, the INCLUDE elements MUST be ignored by user agents.

A policy reference file can only cover URIs on the same host as the reference file. Therefore, the INCLUDE and EXCLUDE elements MUST specify only local URI prefixes; they MUST NOT refer to URIs on other hosts. This requirement does NOT apply to the location of the P3P policy file (the about attribute on the POLICY-REF element).

[13]	include	=	"<INCLUDE>" relativeURI "</INCLUDE>"
[14]	exclude	=	"<EXCLUDE>" relativeURI "</EXCLUDE>"
Here, relativeURI is defined as per RFC 2396 [URI], with the addition that the '*' character is to be treated as a wildcard, as defined in section 2.3.2.1.2.

2.3.2.6 The EMBEDDED-INCLUDE and EMBEDDED-EXCLUDE elements

HTML pages often contain links to other resources that are embedded directly in the page, such as images, sounds, layers or frames. Thus, in order to render the page, the user agents may need to make additional requests that might or might not be covered by the policy in effect for the page that is currently laid out. Because embedded content could be served by a third-party server (and INCLUDE and EXCLUDE MUST specify only local URI prefixes) additional elements are needed to associate a policy with that content.

Each EMBEDDED-INCLUDE or EMBEDDED-EXCLUDE element specifies a third-party absolute URI (see [URI]). These prefixes are used to specify (similarly to INCLUDE and EXCLUDE) the third-party servers who are covered by the policy specified by the about attribute when their content is embedded within the documents on the Web site where the policy reference file resides. However, to limit the scope of when an absolute URI should be considered "embedded", we make use of the HTTP referer header:

When EMBEDDED-INCLUDE (and optionally, EMBEDDED-EXCLUDE) elements are present in a POLICY-REF element, it means that the policy specified in the about attribute of the POLICY-REF element applies to all the URI(s) matched by any EMBEDDED-INCLUDE's, and not matched by an EMBEDDED-EXCLUDE element, when those URIs are requested with a referer header that contains a URI from a resource which is covered by the polsicy reference file containing the embedded URI.

This means that the policy will be applied to objects embedded or linked to, but not objects which are embedded in them. Proxy implementations will be able to examine the referer header generated by the HTTP User-Agent, locate the policy applying to the referer object, and then determine if an embedded content policy is in effect.

User agents SHOULD interpret EMBEDDED-INCLUDE and EMBEDDED-EXCLUDE elements in a policy reference file to determine the policy that applies to third-party content.

Example 2.3 states that /P3P/Policy1.xml applies to all documents in the subtree /docs/ plus the file /other/index.html. In addition, that policy applies to embedded documents requested from the /ads/ directory -- but not the /network/ subdirectory -- on hosts in the adserver.example.com domain.

Example 2.3:

<META xmlns="http://www.w3.org/2000/09/15/P3Pv1">
 <POLICY-REFERENCES>
    <POLICY-REF about="/P3P/Policy1.xml">
      <INCLUDE>/docs/*</INCLUDE>
      <INCLUDE>/other/index.html</INCLUDE>
      <EMBEDDED-INCLUDE>http://*.adserver.example.com/ads/*</EMBEDDED-INCLUDE>
      <EMBEDDED-EXCLUDE>http://*.adserver.example.com/ads/network/*</EMBEDDED-EXCLUDE>
    </POLICY-REF>
 </POLICY-REFERENCES>
</META>

The syntax for the EMBEDDED-INCLUDE and EMBEDDED-EXCLUDE elements is:

[15]	embedded-include	=	"<EMBEDDED-INCLUDE>" absoluteURI "</EMBEDDED-INCLUDE>"
[16]	embedded-exclude	=	"<EMBEDDED-EXCLUDE>" absoluteURI "</EMBEDDED-EXCLUDE>"
Here, absoluteURI is defined as per RFC 2396 [URI], with the addition that the '*' character is to be treated as a wildcard, as defined in section 2.3.2.1.2

Note that sites MAY choose not to specify a policy for some or all of their embedded content. In those cases P3P user agents SHOULD attempt to obtain a P3P policy directly from the site hosting the embedded content.

2.3.2.7 The METHOD element

By default, a policy reference applies to the stated URIs regardless of the method used to access the resource. However, a Web site may wish to define different P3P policies depending on the method to be applied to a resource. For example, a site may wish to collect more data from users when they are performing PUT or DELETE methods than when performing GET methods.

The METHOD element in a policy reference file is used to state that the enclosing policy reference only applies when the specified methods are used to access the referenced resources. The METHOD element may be repeated to indicate multiple applicable methods. If the METHOD element is not present in a POLICY-REF element, then that POLICY-REF element covers the resources indicated regardless of the method used to access them.

So, to state that /P3P/Policy1.xml applies to all documents in the subtree /docs/ for GET and HEAD methods, while /P3P/Policy2.xml applies for PUT and DELETE methods, the following policy reference would be written:

Example 2.5:

<META xmlns="http://www.w3.org/2000/09/15/P3Pv1">
 <POLICY-REFERENCES>
    <POLICY-REF about="/P3P/Policy1.xml">
      <INCLUDE>/docs/*</INCLUDE>
      <METHOD>GET</METHOD>
      <METHOD>HEAD</METHOD>
    </POLICY-REF>
    <POLICY-REF about="/P3P/Policy2.xml">
      <INCLUDE>/docs/*</INCLUDE>
      <METHOD>PUT</METHOD>
      <METHOD>DELETE</METHOD>
    </POLICY-REF>
 </POLICY-REFERENCES>
</META>

Note that HTTP requires the same behavior for GET and HEAD requests, thus it is inappropriate to specify different P3P policies for these methods. The syntax for the METHOD element is:

[17]	method-element	=	`<METHOD>` Method `</METHOD>`
Here, Method is defined in the section 5.1.1 of [HTTP1.1].

2.3.2.8 The POLICIES element

The POLICIES element is used to place P3P policies "in-line" within a policy reference. This is provided as a performance optimization: when a site uses in-line policies in their policy reference files, user agents need only fetch a single file, the policy reference file.

Each policy included in-line in a policy reference file MUST have a name attribute which is unique in the policy reference file. This allows policy references (in POLICY-REF elements) to link to that policy reference file.

There is a trade-off that sites should consider when placing policies in-line in policy reference files. Inline policies allow quicker response time for clients. However, sites have somewhat less flexibility when using inline policies. Inline policies MUST receive the same expiry time as the policy reference file they are included in (see section 2.3.2.2 for details); so, even if an inline policy has its own EXPIRY tag, this expiration information is overriden by the EXPIRY tag of the policy reference file. Merging the policy reference file and the policy into a single file also means that multiple sites under the same authority cannot all link to a single policy file. Site owners should consider whether they wish to use inline policies or seperate their policies from their policy reference files.

[18]	policies	=	"<POLICIES>" *policy "</POLICIES>"
policy is defined in section 3.2.1, The POLICY element.

2.3.3 Forms and Related Mechanisms

Forms deserve special consideration, as they often link to CGI scripts or other server-side applications in their action URIs. It is often the case that those action URIs are covered by a different policy than the form itself.

If a user agent is unable to find a matching prefix for a given action URI in the policy reference file that was referenced from the page, it SHOULD assume that no policy is in effect. Under these circumstances, user agents SHOULD check the well-known location on the host of the action URI to attempt to find a policy reference file that covers the action URI. If this does not provide a P3P policy to cover the action URI, then a user agent MAY try to issue a HEAD request to an action URI before actually submitting any data in order to find the policy in effect. Services SHOULD ensure that server-side applications can properly respond to such HEAD requests and return the corresponding policy reference link in the headers. In case the underlying application does not understand the HEAD request and no policy has been predeclared for the action URI in question, user agents MUST assume that no policy is in effect and SHOULD inform the user about this or take the corresponding actions according to the user's preferences.

Note that services might want to make use of the <METHOD> element in order to declare policies for server-side applications that only cover a subset of supported methods, e.g., POST or GET. Under such circumstances, it is acceptable that the application in question only supports the methods given in the policy reference file (i.e., HEAD requests need not be supported). User agents SHOULD NOT attempt to issue a HEAD request to an action URI if the relevant methods specified in the form's method attribute have been properly predeclared in the page's policy reference file.

In some cases, different data is collected at the same action URI depending on some selection in the form. For example, a search service might offer to both search for people (by name and/or email) and (arbitrary) images. Using a set of radio buttons on the form, a single server-side application located at one and the same action URI handles both cases and collects the required information necessary for the search. If a service wants to predeclare the data collection practices of the server-side application it MAY declare all of the data collection practices in a single policy file (using a <INCLUDE> declaration matching the action URI). In this case, user agents MUST assume that all data elements are collected under every circumstance. This solution offers the convenience of a single policy but might not properly reflect the fact that only parts of the listed data elements are collected at a time. Services SHOULD make sure that a simple HEAD request to the action URI (i.e., without any arguments, especially without the value of the selected radio button) will return a policy that covers all cases.

Note that if a form is handled through use of the GET method, then the action URI reflects the choice of form elements selected by the user. In some cases, it will be possible to make use of the wildcard syntax allowed in policy reference files to specify different policies for different uses of the same form action-handler URI. Therefore, user agents MUST include the query-string portion of URIs when making comparisons with INCLUDE and EXCLUDE elements in policy reference files.

2.4 Additional Requirements

2.4.1 Non-ambiguity

A very important rule of policy references is that of non-ambiguity: For each resource at a website there MUST be at most one policy active at any given time. Thus two non-expired policy reference files on a given site MUST NOT declare two or more different policy URIs for the same resource.

If a policy reference file at the well-known location declares a non-expired policy for a given URI, this policy applies, regardless of any conflicting policy reference files referenced through HTTP headers or HTML link tags.

2.4.2 Multiple Languages

Multiple language versions (translations) of the same policy can be offered by the server using the HTTP "Content-Language" header to properly indicate that a particular language has been used for the policy. This is useful so that human-readable fields such as entity and consequence can be presented in multiple languages. The same mechanism can also be used to offer multiple language versions for data schemas.

Whenever Content-Language is used to distinguish policies at the same URI that are offered in multiple languages, the policies MUST have the same meaning in each language. Two policies (or two data schemas) are taken to be identical if

• All formal (not natural language) protocol elements are semantically identical (i.e., attribute order does not matter, the presence or absence of a default value does not matter, but attribute values matter)
• All natural language protocol elements correspond one-to-one, and for each correspondence, one is a careful translation of the other.

Due to the use of the Accept-Language mechanism, implementors should take note that user agents may see different language versions of a policy or policy reference file despite sending the same Accept-Language request header if a new language version of a policy or data schema has been added.

2.4.3 The "Safe Zone"

Every P3P-enabled user agent and service SHOULD ensure that all the relevant communications that take place as part of fetching a P3P policy are part of a special "safe zone" in which minimal data collection takes place and any data that is collected is used only in non-identifiable ways. In particular, requests to the well-known location for policy reference files SHOULD be covered by these "safe zone" practices.

To support this safe zone, P3P user agents SHOULD suppress the transmission of data unnecessary for the purpose of finding a site's policy until the policy has been fetched. Thus user agents SHOULD NOT send the HTTP Referer header or accept cookies while requesting a P3P policy. User agents MAY also wish to refrain from sending user agent information or cookies accepted in a previous session while requesting a P3P policy. User agent implementors need to be aware that there is a privacy trade-off with using the Accept-Language HTTP header when requesting a P3P policy. Sending the correct Accept-Language header will allow fetching the P3P policy in the user's preferred natural language (if available), but does expose a certain amount of information about the identity of the user. User agents MAY wish to allow users to decide when these headers should be sent.

Servers SHOULD NOT require the receipt of an HTTP Referer header, cookies, user agent information, or other information unnecessary for responding to the request in order to serve a policy file or policy reference file. In addition, servers SHOULD NOT use in an identifiable way any information collected while serving a policy file/policy reference file or responding to a HEAD request.

Servers MAY return a P3P header in the response headers when a P3P policy is requested. However, it is important to note that the P3P header MUST be ignored, and that the "safe zone" requirements described in this section apply instead. Returning a P3P header in such cases is permitted in consideration of the fact that administrators may find it easier to apply a P3P policy to all documents on a server, and that requiring policies to be served without a P3P header may result in extra work for site administrators.

Note that the safe zone requirements do not say that sites cannot keep identifiable information -- only that they SHOULD NOT use in an identifiable way any information collected while serving a policy file. Tracking down the source of a denial of service attack, for example, would be a legitimate reason to use this information and ignore this recommendation.

2.4.4 Non-Discrimination of Policies

Servers SHOULD make every effort to help user agents find P3P policies. In particular, servers SHOULD place a policy reference file at the well-known location whenever possible. When the P3P HTTP header is used as an alternative, servers SHOULD:

Reference a policy in response to any request:

P3P-compliant sites SHOULD include a link to a policy reference file for a web resource whenever possible.

Support HTTP HEAD requests

P3P-compliant servers SHOULD support HEAD requests for any documents that can be retrieved with GET requests. Whenever technically feasible, servers should give a valid response to a HEAD request for documents that are normally accessed by other HTTP methods as well (such as POST).

2.4.5 Security of Policy Transport

P3P policies and references to P3P policies SHOULD NOT, in themselves, contain any sensitive information. This means that there are no additional security requirements for transporting a reference to a P3P policy beyond the requirements of the document it is associated with; so, if an HTML document would normally be served over a non-encrypted session, then the P3P protocol would not require nor recommend that the document be served over an encrypted session when a reference to a P3P policy is included with that document.

2.4.6 Policy Updates

Note that when a web site changes its P3P policy, the old policy applies to data collected when it was in effect. It is the responsibility of the site to keep records of past P3P policies and policy reference files along with the dates when they were in effect, and to apply these policies appropriately.

2.5 Example Scenarios

As an aid to sites deploying P3P, several example scenarios are presented, along with descriptions of how P3P is used on those sites.

Scenario 1: Web site basic.example.com uses a variety of images, all of which it hosts. It also includes some forms, which are all submitted directly to the site. This site can declare a single P3P policy for the entire site (or if different privacy policies apply to different parts of the site, it can declare multiple P3P policies). As long as all of the images and form action URIs are in directories covered by the site's P3P policy, user agents will automatically recognize the images and forms as covered by the site's policy.

Scenario 2: Web site busy.example.com uses a content distribution network called cdn.example.com to host its images so as to reduce the load on its servers. Thus, all of the images on the site have URIs at cdn.example.com. CDN acts as an agent to Busy in this situation, and collects no data other than log data. This log data is used only for web site and system administration in support of providing the services that Busy contracted for. Busy's privacy policy applies to the images hosted by CDN, so Busy uses the EMBEDDED-INCLUDE element in its policy reference file to indicate that its P3P policy applies to embedded content served by cdn.example.com. Optionally, cdn.example.com might also have a policy reference file that declares that the busy.example.com privacy policy applies to these images.

Scenario 3: Web site busy.example.com also has a contract with an advertising company called clickads.example.com to provide banner ads on its site. The contract allows Clickads to set cookies so as to make sure each user doesn't see a given ad more than three times. Clickads collects statistics on how many users view each ad and reports them to the companies whose products are being advertised. But these reports do not reveal information about any individual users. As was the case in Scenario 2, Busy's privacy polices applies to these ads hosted by Clickads, so Busy uses the EMBEDDED-INCLUDE element in its policy reference file to indicate that its P3P policy applies to embedded content served by clickads.example.com. Optionally, clickads.example.com might also have a policy reference file that declares that the busy.example.com privacy policy applies to these ads. The companies whose products are being advertised need not be mentioned in the Busy privacy policy because the only data they are receiving is aggregate data.

Scenario 4: Web site busy.example.com also has a contract with funchat.example.com to host a chat room for its users. When users enter the chat room they are actually leaving the Busy site. However, the chat room has the Busy logo and is actually covered by the Busy privacy policy. In this instance Funchat is acting as an agent for Busy, but -- unlike the previous examples -- their content is not embedded in the Busy site. In this case, there is no way for Busy to include Funchat in its policy reference file. However, Busy should direct Funchat to place a policy reference file on its site that points to the Busy P3P policy.

Scenario 5: Web site bigsearch.example.com has a form that allows users to type in a search query and have it performed on their choice of search engines located on other sites. When a user clicks the "submit" button, the search query is actually submitted directly to these search engines -- the action URI is not on bigsearch.example.com but rather on the search engine selected by the user. Bigsearch cannot declare the privacy policies for these search engines because form actions are not embedded content. So when a user clicks the "submit" button, their user agent should go to the appropriate search engine and check its privacy policy before posting any data. In order to make this search choice mechanism work, Bigsearch might actually have a form with an action URI on its own site, which redirects to the appropriate search engine. In this case, the user agent should check the search engine privacy policy upon receiving the redirect response.

Scenario 6: Web site bigsearch.example.com also has a form that allows users to type in a search query and have it simultaneously performed on ten different search engines. Bigsearch submits the queries, gets back the results from each search engine, removes the duplicates, and presents the results to the user. In this case, the user interacts only with Bigsearch. Thus, the only P3P policy involved is the one that covers the Bigsearch web site. However, Bigsearch must disclose that it shares the users' search queries with third parties (the search web sites), unless Bigsearch has a contract with these search engines and they act as agents to Bigsearch.

Scenario 7: Web site bigsearch.example.com also has banner advertisements provided by a company called adnetwork.example.com. Adnetwork uses cookies to develop profiles of users across many different web sites so that it can provide them with ads better suited to their interests. Because the data about the sites that users are visiting is being used for purposes other than just serving ads on the Bigsearch web site, Adnetwork cannot be considered an agent in this context. Adnetwork must create its own P3P policy and use its own policy reference file to indicate what content it applies to. In addition, Bigsearch may optionally use the EMBEDDED-INCLUDE element in its policy reference file to indicate that the Adnetwork P3P policy applies to these advertisements. Bigsearch should only do this if Adnetwork has told it what P3P policy applies to these advertisements and has agreed to notify Bigsearch if the policy reference needs to be changed.

3. Policy Syntax and Semantics

P3P policies are encoded in XML. They may also be represented using the RDF data model ([RDF]); however, an RDF representation is not included in this specification. (The working group plans to make this available as a W3C Note prior to submitting P3P as a Proposed Recommendation, together with a suitable RDF encoding of the policy reference file).

Section 3.1 begins with an example of an English language privacy policy and a corresponding P3P policy. P3P policies include general assertions that apply to the entire policy as well as specific assertions -- called statements -- that apply only to the handling of particular types of data referred to by data references. Section 3.2 describes the policy element and policy-level assertions. Section 3.3 describes statements and data references.

3.1 Example policies

3.1.1 English language policies

The following are two examples of English-language privacy policy to be encoded as a P3P policy. Both policies are for one example company, CatalogExample, which has different policies for those browsing their site and those actually purchasing products. Example 3.1. is provided in both English and as a more formal description using P3P element and attribute names.

Example 3.1: CatalogExample's Privacy Policy for Browsers

At CatalogExample, we care about your privacy. When you come to our site to look for an item, we will only use this information to improve our site and will not store it in an identifiable way.

CatalogExample, Inc. is a licensee of the PrivacySealExample Program. The PrivacySealExample Program ensures your privacy by holding Web site licensees to high privacy standards and confirming with independent auditors that these information practices are being followed.

Questions regarding this statement should be directed to:
CatalogExample
4000 Lincoln Ave.
Birmingham, MI 48009 USA
E-mail: catalog@example.com
Telephone 248-EXAMPLE (248-392-6753)

If we have not responded to your inquiry or your inquiry has not been satisfactorily addressed, you can contact PrivacySealExample at http://www.privacyseal.example.org. CatalogExample will correct all errors or wrongful actions arising in connection with the privacy policy.

What We Collect and Why:
When you browse through our site we collect:

• the basic information about your computer and connection to make sure that we can get you the proper information and for security purposes.
• aggregate information on what pages consumers access or visit to improve our site.

Data retention:
We purge every two weeks the browsing information that we collect.

Here is Example 3.1 in a more formal description, using the P3P element and attribute names [with the section of the spec that was used cited in brackets for easy reference]:

• Disclosure URI: http://www.catalog.example.com/PrivacyPracticeBrowsing.html
  [3.2.1 Policy]
• Entity: CatalogExample
  4000 Lincoln Ave.
  Birmingham, MI 48009
  USA
  catalog@example.com
  +1 (248) 392-6753
  [3.2.2 Entity]
• Access to Identifiable Information: None
  [3.2.3 Access]
• Disputes:
  resolution type: independent
  service: http://www.privacyseal.example.org
  description: PrivacySealExample
  [3.2.4 Disputes]
• Remedies: we'll correct any harm done wrong
  [3.2.5 Remedies]
• We collect:
  dynamic.clickstream.server
  dynamic.http.useragent
  [4.5 Base Data Schema]
• For purpose: Web site and system administration, research and development
  [3.3.3 Purpose]
• Recipients: Only ourselves and our agents
  [3.3.4 Recipients]
• Retention: As long as appropriate for the stated purposes
  [3.3.5 Retention]
  (Note also that the site's human-readable privacy policy MUST mention that data is purged every two weeks, or provide a link to this information.)

Example 3.2: CatalogExample's Privacy Policy for Shoppers

At CatalogExample, we care about your privacy. We will never share your credit card number or any other financial information with any third party. With your permission only, we will share information with carefully selected marketing partners that meet either the preferences that you've specifically provided or your past purchasing habits. The more we and know about your likes and dislikes, the better we can tailor offerings to your needs.

CatalogExample is a licensee of the PrivacySealExample Program. The PrivacySealExample Program ensures your privacy by holding Web site licensees to high privacy standards and confirming with independent auditors that these information practices are being followed.

Questions regarding this statement should be directed to:
CatalogExample
4000 Lincoln Ave.
Birmingham, MI 48009 USA
E-mail: catalog@example.com
Telephone +1 248-EXAMPLE (+1 248-392-6753)

If we have not responded to your inquiry or your inquiry has not been satisfactorily addressed, you can contact PrivacySealExample - http://privacyseal.example.org/privacyseal. CatalogExample will correct all errors or wrongful actions arising in connection with the privacy policy.

When you browse through our site we collect:

• the basic information about your computer and connection to make sure that we can get you the proper information and for security purposes; and
• aggregate information on what pages consumers access or visit to improve our site

If you choose to purchase an item we will ask you for more information including:

• your name and address so that we can have your purchase delivered to you and so we can contact you in the future;
• your email address and telephone number so we can contact you;
• a login and password to use to update your information at any time in the future; and
• financial information to complete your purchase (you may choose to store this for future use)
• optionally, you can enter other demographic information so that we can tailor services to you in the future.

Also on this page we will give you the option to choose if you would like to receive email, telephone calls or written service from CatalogExample or from our carefully selected marketing partners who maintain similar privacy practices. If you would like to receive these solicitations simply check the appropriate boxes. You can choose to stop participating at any time simply by changing your preferences.

Changing and Updating personal information
Consumers can change all of their personal account information by going to the preferences section of CatalogExample at http://catalog.example.com/preferences.html. You can change your address, telephone number, e-mail address, password as well as your privacy settings.

Cookies
CatalogExample uses cookies only to see if you have been an CatalogExample customer in the past and, if so, customize services based on your past browsing habits and purchases. We do not store any personal data in the cookie nor do we share or sell the any of the information with other parties or affiliates.

Data retention
We will keep the information about you and your purchases for as long as you remain our customer. If you do not place an order from us for one year we will remove your information from our databases.

3.1.2 XML encoding of policies

The following pieces of [XML] capture the information as expressed in the above two examples. P3P policies are statements that are properly expressed as well-formed XML. The policy syntax will be explained in more detail in the sections that follow.

XML Encoding of Example 3.1:

<POLICY xmlns="http://www.w3.org/2000/09/15/P3Pv1"
    discuri="http://www.catalog.example.com/PrivacyPracticeBrowsing.html">
 <ENTITY>
  <DATA-GROUP>
   <DATA ref="#business.name">CatalogExample</DATA>
   <DATA ref="#business.contact-info.postal.street">4000 Lincoln Ave.</DATA>
   <DATA ref="#business.contact-info.postal.city">Birmingham</DATA>
   <DATA ref="#business.contact-info.postal.stateprov">MI</DATA>
   <DATA ref="#business.contact-info.postal.postalcode">48009</DATA>
   <DATA ref="#business.contact-info.postal.country">USA</DATA>
   <DATA ref="#business.contact-info.online.email">catalog@example.com</DATA>
   <DATA ref="#business.contact-info.telecom.telephone.intcode">1</DATA>
   <DATA ref="#business.contact-info.telecom.telephone.loccode">248</DATA>
   <DATA ref="#business.contact-info.telecom.telephone.number">3926753</DATA>
  </DATA-GROUP>
 </ENTITY>
 <ACCESS><nonident/></ACCESS>
 <DISPUTES-GROUP>
  <DISPUTES resolution-type="independent"
    service="http://www.PrivacySeal.example.org"
    short-description="PrivacySeal.example.org">
   <IMG src="http://www.PrivacySeal.example.org/Logo.gif" alt="PrivacySeal's logo"/>
   <REMEDIES><correct/></REMEDIES>
  </DISPUTES>
 </DISPUTES-GROUP>
 <STATEMENT>
  <PURPOSE><admin/><develop/></PURPOSE>
  <RECIPIENT><ours/></RECIPIENT>
  <RETENTION><stated-purpose/></RETENTION> <!-- Note also that the site's human-readable
                                                privacy policy MUST mention that data 
                                                is purged every two weeks, or provide a 
                                                link to this information. -->
  <DATA-GROUP>
   <DATA ref="#dynamic.clickstream.clientip"/>
   <DATA ref="#dynamic.http.useragent"/>
  </DATA-GROUP>
 </STATEMENT>
</POLICY>

XML Encoding of Example 3.2:

<POLICY xmlns="http://www.w3.org/2000/09/15/P3Pv1"
    discuri="http://www.catalog.example.com/Privacy/PrivacyPracticeShopping.html"
    opturi="http://catalog.example.com/preferences.html">
 <ENTITY>
  <DATA-GROUP>
   <DATA ref="#business.name">CatalogExample</DATA>
   <DATA ref="#business.contact-info.postal.street">4000 Lincoln Ave.</DATA>
   <DATA ref="#business.contact-info.postal.city">Birmingham</DATA>
   <DATA ref="#business.contact-info.postal.stateprov">MI</DATA>
   <DATA ref="#business.contact-info.postal.postalcode">48009</DATA>
   <DATA ref="#business.contact-info.postal.country">USA</DATA>
   <DATA ref="#business.contact-info.online.email">catalog@example.com</DATA>
   <DATA ref="#business.contact-info.telecom.telephone.intcode">1</DATA>
   <DATA ref="#business.contact-info.telecom.telephone.loccode">248</DATA>
   <DATA ref="#business.contact-info.telecom.telephone.number">3926753</DATA>
  </DATA-GROUP>
 </ENTITY>
 <ACCESS><contact_and_other/></ACCESS>
 <DISPUTES-GROUP>
  <DISPUTES resolution-type="independent"
    service="http://www.PrivacySeal.example.org"
    short-description="PrivacySeal.example.org">
   <IMG src="http://www.PrivacySeal.example.org/Logo.gif" alt="PrivacySeal's logo"/>
   <REMEDIES><correct/></REMEDIES>
  </DISPUTES>
 </DISPUTES-GROUP>
 <STATEMENT>
  <PURPOSE><admin/><develop/></PURPOSE>
  <RECIPIENT><ours/></RECIPIENT>
  <RETENTION><stated-purpose/></RETENTION>
  <DATA-GROUP>
   <DATA ref="#dynamic.clickstream.server"/>
   <DATA ref="#dynamic.http.useragent"/>
  </DATA-GROUP>
 </STATEMENT>
 <STATEMENT>
  <PURPOSE><current/></PURPOSE>
  <RECIPIENT><ours/></RECIPIENT>
  <RETENTION><stated-purpose/></RETENTION>
  <DATA-GROUP>
   <DATA ref="#user.name"/>
   <DATA ref="#user.home-info.postal"/>
   <DATA ref="#user.home-info.telecom.telephone"/>
   <DATA ref="#user.business-info.postal"/>
   <DATA ref="#user.business-info.telecom.telephone"/>
   <DATA ref="#user.home-info.online.email"/>
   <DATA ref="#dynamic.miscdata">
    <CATEGORIES><financial/></CATEGORIES>
   </DATA>
  </DATA-GROUP>
 </STATEMENT>
 <STATEMENT>
  <PURPOSE>
   <contact required="opt_out"/>
   <customization required="opt_out"/>
   <tailoring required="opt_out"/>
  </PURPOSE>
  <RECIPIENT><ours/><same/></RECIPIENT>
  <RETENTION><stated-purpose/></RETENTION>
  <DATA-GROUP>
   <DATA ref="#user.name" optional="yes"/>
   <DATA ref="#user.home-info.postal" optional="yes"/>
   <DATA ref="#user.home-info.telecom.telephone" optional="yes"/>
   <DATA ref="#user.business-info.postal" optional="yes"/>
   <DATA ref="#user.business-info.telecom.telephone" optional="yes"/>
   <DATA ref="#user.home-info.online.email" optional="yes"/>
  </DATA-GROUP>
 </STATEMENT>
 <STATEMENT>
  <CONSEQUENCE>Lets you access your own information</CONSEQUENCE>
  <PURPOSE><customization required="opt_out"/></PURPOSE>
  <RECIPIENT><ours/><same/></RECIPIENT>
  <RETENTION><stated-purpose/></RETENTION>
  <DATA-GROUP>
   <DATA ref="#dynamic.miscdata">
    <CATEGORIES><uniqueid/></CATEGORIES>
   </DATA>
  </DATA-GROUP>
 </STATEMENT>
 <STATEMENT>
  <CONSEQUENCE>A site with products you would appreciate</CONSEQUENCE>
  <PURPOSE>
    <customization required="opt_out"/>
    <tailoring required="opt_out"/>
  </PURPOSE>
  <RECIPIENT><ours/><same/></RECIPIENT>
  <RETENTION><stated-purpose/></RETENTION>
  <DATA-GROUP>
   <DATA ref="#user.bdate.ymd.year" optional="yes"/>
   <DATA ref="#user.gender" optional="yes"/>
  </DATA-GROUP>
 </STATEMENT>
 <STATEMENT>
  <CONSEQUENCE>A site with clothes you would appreciate</CONSEQUENCE>
  <PURPOSE><customization/><develop/></PURPOSE>
  <RECIPIENT><ours/></RECIPIENT>
  <RETENTION><business-practices/></RETENTION> <!-- Note also that the site's human-readable privacy 
                                                    policy MUST mention the corresponding practices, 
                                                    or provide a link to this information -->
  <DATA-GROUP>
   <DATA ref="#dynamic.cookies">
    <CATEGORIES><state/></CATEGORIES>
   </DATA>
   <DATA ref="#dynamic.miscdata">
    <CATEGORIES><preference/></CATEGORIES>
   </DATA>
  </DATA-GROUP>
 </STATEMENT>
</POLICY>

3.2 Policies

This section defines the syntax and semantics of P3P policies. All policies MUST be encoded using [UTF-8]. P3P servers MUST encode their policies using this encoding. P3P user agents MUST be able to parse this syntax.

3.2.1 The POLICY element

The POLICY element contains a complete P3P policy. Each P3P policy MUST contain exactly one POLICY element. The policy element MUST contain an ENTITY element that identifies the legal entity making the representation of the privacy practices contained in the policy. In addition, the policy element MUST contain an ACCESS element, and optionally STATEMENT elements, a DISPUTES-GROUP element, an EXPIRY element (indicating the expiration of the policy), a P3P dataschema, and one or more extensions.

<POLICY>

includes one or more statements. Each statement includes a set of disclosures as applied to a set of data elements.

discuri (mandatory attribute)

URI of the natural language privacy statement

opturi

URI of instructions that users can follow to request or decline to have their data used for a particular purpose (opt-in or opt-out). This attribute is mandatory for policies that contain a purpose with required attribute set to opt-in or opt-out.

name

name of the policy, used as fragment identifier to be able to reference the policy

policy

=

`<POLICY xmlns="http://www.w3.org/2000/09/15/P3Pv1"
         discuri=` quoted-URI 
         [` opturi=` quoted-URI]
         [` name=` quotedstring] `>`
*extension
[expiry]
[dataschema]
entity
access
[disputes-group]
*statement-block
*extension
`</POLICY>`

quoted-URI

=

`"` URI `"`

3.2.2 The ENTITY element

The ENTITY element gives a precise description of the legal entity making the representation of the privacy practices.

<ENTITY>

identifies the legal entity making the representation of the privacy practices contained in the policy

The ENTITY element contains a description of the legal entity consisting of DATA elements referencing (all or some of) the fields of the business dataset: it MUST contain both the legal entity's name as well as contact information such as postal address, telephone number, email address, or other information that individuals may use to contact the entity about their privacy policy. Note that some laws and codes of conduct require entities to include a postal address or other specific information in their contact information.

[21]	entity	=	"<ENTITY>" *extension entitydescription *extension "</ENTITY>"
[22]	entitydescription	=	"<DATA-GROUP>" `<DATA ref="#business.name"/>` PCDATA "</DATA>" *(`<DATA ref="#business.` string `"/>` PCDATA "</DATA>") "</DATA-GROUP>"
Here, string is defined as a sequence of characters (with " and & escaped) among the values that are allowed by the business dataset. PCDATA is defined as in [XML].

3.2.3 The ACCESS element

The ACCESS element indicates whether the site provides access to various kinds of information.

<ACCESS>

the ability of the individual to view identifiable information and address questions or concerns to the service provider. Service providers MUST disclose one value for the access attribute. The method of access is not specified. Any disclosure is not meant to imply that access to all data is possible, but that some of the data may be accessible and that the user should communicate further with the service provider to determine what capabilities they have.

Note that service providers may also wish to provide capabilities to access information collected through means other than the Web at the discuri. However, the scope of P3P statements are limited to data collected through HTTP or other Web transport protocols. Also, if access is provided through the Web, use of strong authentication and security mechanisms for such access is recommended; however, security issues are outside the scope of this document.

The ACCESS element must contain one of the following elements:

<nonident/>

Identifiable Data is Not Used

<all/>

All Identifiable Information: access is given to all identifiable information.

<contact_and_other/>

Identifiable Contact Information and Other Identifiable Information: access is given to identifiable online and physical contact information as well as to other information linked to an identifiable person.

<ident_contact/>

Identifiable Contact Information: access is given to identifiable online and physical contact information (e.g., users can access things such as a postal address).

<other_ident/>

Other Identifiable Information: access is given to certain other information linked to an identifiable person (e.g., users can access things such as their online account charges).

<none/>

None: no access to identifiable information is given.

[23]	access	=	"<ACCESS>" access_disclosure *extension "</ACCESS>"
[24]	access-disclosure	=	"<nonident/>" | ; Identifiable Data is Not Used "<ident_contact/>" | ; Identifiable Contact Information "<other_ident/>" | ; Other Identifiable Information "<contact_and_other/>" | ; Identifiable and Other Contact Information "<all/>" | ; All Identifiable Information "<none/>" ; None

3.2.4 The DISPUTES element

A policy SHOULD contain a DISPUTES-GROUP element, which contains one or more DISPUTES elements. These elements describe dispute resolution procedures that may be followed for disputes about a services' privacy practices. Each DISPUTES element can optionally contain a LONG-DESCRIPTION element, an IMG element, and a REMEDIES element. Service providers with multiple dispute resolution procedures should use a separate DISPUTES element for each. Since different dispute procedures have separate remedy processes, each DISPUTES element would need a separate LONG-DESCRIPTION, IMG tag and REMEDIES element, if they are being used.

<DISPUTES>

Describes dispute resolution procedures that may be followed for disputes about a services' privacy practices, or in case of protocol violation.

resolution-type (mandatory attribute)

takes one of the following four values:

Customer service [service]

Individual may complain to the web site's customer service representative for resolution of disputes regarding the use of collected data. The description MUST include information about how to contact customer service.

Independent organization [independent]

Individual may complain to an independent organization for resolution of disputes regarding the use of collected data. The description MUST include information about how to contact the third party organization.

Court [court]

Individual may file a legal complaint against the web site.

Applicable law [law]

Disputes arising in connection with the privacy statement will be resolved in accordance with the law referenced in the description.

service (mandatory attribute)

URI of the customer service web page or independent organization, or URI for information about the relevant court or applicable law

verification

URI or certificate that can be used for verification purposes. It is anticipated that seal providers will provide a mechanism for verifying a site's claim that they have a seal.

short-description

A short human readable description of the name of the appropriate legal forum, applicable law, or third party organization; or contact information for customer service if not already provided at the service URI. No more than 255 characters.

The DISPUTES element can contain a LONG-DESCRIPTION element, where a human readable description is present: this should contain the name of the appropriate legal forum, applicable law, or third party organization; or contact information for customer service if not already provided at the service URI.

<LONG-DESCRIPTION>

This element contains a (possibly long) human readable description.

<IMG>

An image logo (for example, of the independent organization or relevant court)

src (mandatory attribute)

URI of the image logo

width

width in pixels of the image logo

height

height in pixels of the image logo

alt (mandatory attribute)

very short textual alternative for the image logo

[25]	disputes-group	=	"<DISPUTES-GROUP>" 1*dispute *extension "</DISPUTES-GROUP>"
[26]	dispute	=	"<DISPUTES" " resolution-type=" '"'("service"|"independent"|"court"|"law")'"'  " service=" quoted-URI [" verification=" quotedstring] [" short-description=" quotedstring] ">" *extension [longdescription] [image] [remedies] *extension "</DISPUTES>"
[27]	longdescription	=	<LONG-DESCRIPTION> PCDATA </LONG-DESCRIPTION>
[28]	image	=	"<IMG src=" quoted-URI [" width=" `"` number `"`] [" height=" `"` number `"`] " alt=" quotedstring "/>"
[29]	quotedstring	=	`"` string `"`
Here, string is defined as a sequence of characters (with " and & escaped), and PCDATA is defined as in [XML].

Note that there can be multiple assurance services, specified via multiple occurrences of DISPUTES within the DISPUTES-GROUP element. These fields are expected to be used in a number of ways, including representing that one's privacy practices are self assured, audited by a third party, or under the jurisdiction of a regulatory authority.

3.2.5 The REMEDIES element

Each DISPUTES element SHOULD contain a REMEDIES element that specifies the possible remedies in case a policy breach occurs.

<REMEDIES>

Remedies in case a policy breach occurs.

The REMEDIES element must contain one or more of the following:

<correct/>

Errors or wrongful actions arising in connection with the privacy policy will be remedied by the service.

<money/>

If the service provider violates its privacy policy it will pay the individual an amount specified in the human readable privacy policy or the amount of damages.

<law/>

Remedies for breaches of the policy statement will be determined based on the law referenced in the human readable description.

remedies

=

"<REMEDIES>" 
1*remedy
*extension
"</REMEDIES>"

remedy

=

"<correct/>" | 
"<money/>"   |
"<law/>"
        

3.3 Statements

Statements describe data practices that are applied to particular types of data.

3.3.1 The STATEMENT element

The STATEMENT element is a container that groups together a PURPOSE element, a RECIPIENT element, a RETENTION element, a DATA-GROUP element, and optionally a CONSEQUENCE element and one or more extensions. All of the data referenced by the DATA-GROUP is handled according to the disclosures made in the other elements contained by the statement. Thus, sites may group elements that are handled the same way and create a statement for each group. Sites that would prefer to disclose separate purposes and other information for each kind of data they collect can do so by creating a separate statement for each data element.

<STATEMENT>

data practices as applied to data elements.

[32]

statement-block

=

"<STATEMENT>" *extension [consequence] purpose recipient retention 1*data-group *extension "</STATEMENT>"

To simplify practice declaration, service providers may aggregate any of the disclosures (purposes, recipients, and identifiable use) within a statement over data elements. Service providers MUST make such aggregations as an additive operation. For instance, a site that distributes your age to ours (ourselves and our agents), but distributes your zip code to unrelated (unrelated third parties), MAY say they distribute your name and zip code to ours and unrelated. Such a statement appears to distribute more data than actually happens. It is up to the service provider to determine if their disclosure deserves specificity or brevity.

Also, one must always disclose all options that apply. Consider a site with the sole purpose of collecting information for the purposes of contact (Contacting Visitors for Marketing of Services or Products). Even though this is considered to be for the current (Completion and Support of Current Activity) purpose, the site must state both contact and current purposes. Consider a site which distributes information to ours in order to redistribute it to public: the site must state both ours and public recipients.

Service providers often aggregate data they collect. Sometimes this aggregate data may be used for different purposes than the original data, shared more widely than the original data, or retained longer than the original data. For example many sites  publish or disclose to their advertisers statistics such as  number of visitors to their web site, percentage of visitors  who fit into various demographic groups, etc. When  aggregate statistics are used or shared such that it would not be possible to derive data for individual  people or households based on these statistics, no  disclosures about these statistics are necessary in a P3P policy. However, services MUST disclose the fact that the original data is collected and declare any use that is made of the data before it is aggregated.

3.3.2 The CONSEQUENCE element

STATEMENT elements may optionally contain a CONSEQUENCE element that can be shown to a human user to provide further explanation about a site's practices.

<CONSEQUENCE>

Consequences that can be shown to a human user to explain why the suggested practice may be valuable in a particular instance even if the user would not normally allow the practice.

[33]

consequence

=

"<CONSEQUENCE>" PCDATA "</CONSEQUENCE>"

3.3.3 The PURPOSE element

Each STATEMENT element MUST contain a PURPOSE element that contains one or more purposes of data collection or uses of data. Sites MUST classify their data practices into one or more of the purposes specified below.

<PURPOSE>

purposes for data processing relevant to the Web.

The PURPOSE element MUST contain one or more of the following:

<current/>

Completion and Support of Current Activity: Information may be used to contact the individual, through a communications channel other than voice telephone, for the promotion of a product or service (for example to return the results from a Web search, to forward email, or place an order).

<admin/>

Web Site and System Administration: Information may be used for the technical support of the Web site and its computer system. This would include processing computer account information, information used in the course of securing and maintaining the site, and verification of web site activity by the site or its agents.

<develop/>

Research and Development: Information may be used to enhance, evaluate, or otherwise review the site, service, product, or market. This does not include personal information used to tailor or modify the content to the specific individual nor information used to evaluate, target, profile or contact the individual.

<customization/>

Affirmative Customization: Information may be used to tailor or modify the content or design of the site only to specifications affirmatively selected by the particular individual during a single visit or multiple visits to the site. For example, a financial site that lets users select several stocks whose current prices are displayed whenever the user visits.

<tailoring/>

One-time Tailoring: Information may be used to tailor or modify content or design of the site not affirmatively selected by the particular individual where the information is used only for a single visit to the site and not used for any kind of future customization. For example, an online store that suggests other items a visitor may wish to purchase based on the items he has already placed in his shopping basket.

<pseudo-analysis/>

Pseudonymous Analysis: Information may be used to create or build a record of a particular individual or computer that is tied to a pseudonymous identifier, without tying personally-identifiable information (such as name, address, phone number, email address, or IP address) to the record. This profile will be used to determine the habits, interests, or other characteristics of individuals for purpose of research, analysis and reporting, but it will not be used to attempt to identify specific individuals. For example, a marketer may wish to understand the interests of visitors to different portions of a web site.

<pseudo-decision/>

Pseudonymous Decision: Information may be used to create or build a record of a particular individual or computer that is tied to a pseudonymous identifier, without tying personally-identifiable information (such as name, address, phone number, email address, or IP address) to the record. This profile will be used to determine the habits, interests, or other characteristics of individuals to make a decision that directly affects that individual, but it will not be used to attempt to identify specific individuals. For example, a marketer may tailor or modify content displayed to the browser based on pages viewed during previous visits.

<individual-analysis/>

Individual Analysis: Information may be used to determine the habits, interests, or other characteristics of individuals and combine it with personally identifiable information for the purpose of research, analysis and reporting. For example, an online web site for a physical store may wish to analyze how online shoppers make offline purchases.

<individual-decision/>

Individual Decision:  Information may be used to determine the habits, interests, or other characteristics of individuals and combine it with personally identifiable information to make a decision that directly affects that individual.  For example, an online store suggests items a visitor may wish to purchase based on items he has purchased during previous visits to the web site.

<contact/>

Contacting Visitors for Marketing of Services or Products: Information may be used to contact the individual for the promotion of a product or service. This includes notifying visitors about updates to the Web site. This does not include a direct reply to a question or comment or customer service for a single transaction -- in those cases, <current/> would be used. In addition, this does not include marketing via customized web content or banner advertisements embedded in sites the user is visiting -- these cases would be covered by the <tailoring/>, <pseudonym/>, or <profiling/> purposes.

<historical/>

Historical Preservation: Information may be archived or stored for the purpose of preserving social history as governed by an existing law or policy. This law or policy MUST be referenced in the <DISPUTES> element and MUST include a specific definition of the type of qualified researcher who can access the information, where this information will be stored and specifically how this collection advances the preseservation of history.

<telemarketing/>

Contacting Visitors for Marketing of Services or Products Via Telephone: Information may be used to contact the individual via a voice telephone call for promotion of a product or service. This does not include a direct reply to a question or comment or customer service for a single transaction -- in those cases, <current/> would be used.

<other-purpose> string </other-purpose>

Other Uses: Information may be used in other ways not captured by the above definitions. (A human readable explanation should be provided in these instances).

Each type of purpose can have the following optional attribute:

required

Whether the purpose is a required practice for the site. The attribute can take the following values:

• always : The purpose is always required; users cannot opt-in or opt-out of this use of their data. This is the default when no required attribute is present.
• opt_in : Data may be used for this purpose only when the user affirmatively requests this use -- for example, when a user asks to be added to a mailing list. An affirmative request requires users to take some action specifically to make the request. For example, when users fill out a survey, checking an additional box to request to be added to a mailing list would be considered an affirmative request. However, submitting a survey form that contains a pre-checked mailing list request box would not be considered an affirmative request. In addition, for any purpose that users may affirmatively request, there must also be a way for them to change their minds later and decline -- this MUST be specified at the opturi.
• opt_out :Data may be used for this purpose unless the user requests that it not be used in this way. When this value is selected, the service MUST provide clear instructions to users on how to opt-out of this purpose at the opturi. Services SHOULD also provide these instructions or a pointer to these instructions at the point of data collection.

[34]	purpose	=	"<PURPOSE>" 1*purposevalue *extension "</PURPOSE>"
[35]	purposevalue	=	"<current" [required] "/>" | ; Completion and Support of Current Activity "<admin" [required] "/>" | ; Web Site and System Administration "<develop" [required] "/>" | ; Research and Development "<customization" [required] "/>" | ; Affirmative Customization "<tailoring" [required] "/>" | ; One-time Tailoring "<pseudo-analysis" [required] "/>" | ; Pseudonymous Analysis "<pseudo-decision" [required] "/>" | ; Pseudonymous Decision "<individual-analysis" [required] "/>" | ; Individual Analysis "<individual-decision" [required] "/>" | ; Individual Decision "<contact" [required] "/>" | ; Contacting Visitors for Marketing of Services or Products "<historical" [required] "/>" | ; Historical Preservation "<telemarketing" [required] "/>" | ; Telephone Marketing "<other-purpose" [required] ">" PCDATA "</other-purpose>"; Other Uses
[36]	required	=	" required=" `"` ("always"|"opt_in"|"opt_out") `"`

Service providers MUST use the above elements to explain the purpose of data collection. Service providers MUST disclose all that apply. If a service provider does not disclose that a data element will be used for a given purpose, that is a representation that data will not be used for that purpose. Service providers that disclose that they use data for "other" purposes MUST provide human readable explanations of those purposes.

Note, that the working group discussed at length the possibility of allowing sites to distinguish between purposes they may engage in and purposes they will engage in. The consensus of the working group was that such a distinction is not necessary. However, some members disagreed with this conclusion stating:

Yes, no and may all need to be response options in the vocabulary. If no and may are the only options, then the meaning of may is corrupted to equal yes. May should be an option that reflects its true meaning -- yes or no. If may by default means yes, because yes is not provided as a response option, the consumer will be misled. May should be used to imply that there are a set of rules underlying the term that consumers can refer to understand a privacy policy. If may means yes, the consumer is less likely to investigate via a click-through to the Web site's privacy policy. Potentially, this seemingly simple solution -- no and may -- will be a significant barrier to commerce as consumers are confused by the meaning of the truncated choices of only no and may. Those who argue that providing all three choices -- yes, may, no -- is an attempt by Web sites to mislead consumers are missing the point. In the arena of privacy protection, accuracy in stating a privacy policy is critical to building trust and confidence in the consumer about how information is used. In the interest of software simplicity, limiting consumer preference choices to no and may will do a disservice to the consumer -- and to the Web sites that are trying to communicate accurately with consumers about their policies.

3.3.4 The RECIPIENT element

Each STATEMENT element MUST contain a RECIPIENT element that contains one or more recipients of the collected data. Sites MUST classify their recipients into one or more of the six recipients specified.

<RECIPIENT>

the legal entity, or domain, beyond the service provider and its agents where data may be distributed.

The RECIPIENT element MUST contain one or more of the following:

<ours>

Ourselves and/or our entities acting as our agents or entities for whom we are acting as an agent: An agent in this instance is defined as a third party that processes data only on behalf of the service provider for the completion of the stated purposes. (e.g., the service provider and its printing bureau which prints address labels and does nothing further with the information.)

<delivery>

Delivery services possibly following different practices: Legal entities performing delivery services that may use data for purposes other than completion of the stated purpose. This should also be used for delivery services whose data practices are unknown.

<same>

Legal entities following our practices: Legal entities who use the data on their own behalf under equable practices. (e.g., consider a service provider that grants the user access to collected personal information, and also provides it to a partner who uses it once but discards it. Since the recipient, who has otherwise similar practices, cannot grant the user access to information that it discarded, they are considered to have equable practices.)

<other-recipient>

Legal entities following different practices: Legal entities that are constrained by and accountable to the original service provider, but may use the data in a way not specified in the service provider's practices (e.g. The service provider collects data that is shared with a partner who may use it for other purposes. However, it is in the service provider's interest to ensure that the data is not used in a way that would be considered abusive to the users' and its own interests.)

<unrelated>

Unrelated third parties: Legal entities whose data usage practices are not known by the original service provider.

<public>

Public fora: Public fora such as bulletin boards, public directories, or commercial CD-ROM directories.

Each of the above tags can optionally contain one or more recipient-description tags, containing a description of the recipient, and, with the exception of <ours/>, a required tag (analogously to PURPOSEs), indicating whether opt-in/opt-out of sharing is available.

[37]	recipient	=	"<RECIPIENT>" 1*recipientvalue *extension "</RECIPIENT>"
[38]	recipientvalue	=	"<ours>" *recdescr "</ours> | ; only ourselves and our agents "<same" [required] ">" *recdescr "</same>" | ; legal entities following our practices "<other-recipient" [required] ">" *recdescr "</other-recipient>" | ; legal entities following different practices "<delivery" [required] ">" *recdescr "</delivery>" | ; delivery services following different practices "<public" [required] ">" *recdescr "</public>" | ; public fora "<unrelated" [required] ">" *recdescr "</unrelated>" ; unrelated third parties
[39]	recdescr	=	"<recipient-description>" PCDATA ; description of the recipient "</recipient-description>"

Service providers MUST disclose all the recipients that apply. Note that in some cases the above set of recipients may not completely describe all the recipients of data. For example, the issue of transaction facilitators, such as shipping or payment processors, who are necessary for the completion and support of the activity but may follow different practices was problematic. Currently, only delivery services can be explicitly represented in a policy. Other such transaction facilitators should be represented in whichever category most accurately reflects their practices with respect to the original service provider. The working group decided to include a special element for delivery services, but not for payment processors (such as banks or credit card companies) for the following reasons: Financial institutions will typically have separate agreements with their customers regarding the use of their financial data, while delivery recipients typically do not have an opportunity to review a delivery service's privacy policy.

Note that the <delivery/> element SHOULD NOT be used for delivery services that agree to use data only on behalf of the service provider for completion of the delivery.

3.3.5 The RETENTION element

Each STATEMENT element MUST contain a RETENTION element that indicates the kind of retention policy that applies to the data referenced in that statement.

<RETENTION>

the type of retention policy in effect

The RETENTION element MUST contain one of the following:

<no-retention/>

Information is not retained for more than a brief period of time necessary to make use of it during the course of a single online interaction. Information MUST be destroyed following this interaction and MUST not be logged, archived, or otherwise stored. This type of retention policy would apply, for example, to services that keep no Web server logs, set cookies only for use during a single session, or collect information to perform a search but do not keep logs of searches performed.

<stated-purpose/>

For the stated purpose: Information is retained to meet the stated purpose. This requires information to be discarded at the earliest time possible. Sites MUST have a retention policy that establishes a destruction time table. The retention policy MUST be included in or linked from the site's human-readable privacy policy.

<legal-requirement/>

As required by law or liability under applicable law: Information is retained to meet a stated purpose, but the retention period is longer because of a legal requirement or liability. For example, a law may allow consumers to dispute transactions for a certain time period; therefore a business may for liability reasons decide to maintain records of transactions, or a law may affirmatively require a certain business to maintain records for auditing or other soundness purposes. Sites MUST have a retention policy that establishes a destruction time table. The retention policy MUST be included in or linked from the site's human-readable privacy policy.

<business-practices/>

Determined by service provider's business practice: Information is retained under a service provider's stated business practices. Sites MUST have a retention policy that establishes a destruction time table. The retention policy MUST be included in or linked from the site's human-readable privacy policy.

<indefinitely/>

Indefinitely: Information is retained for an indeterminate period of time. The absence of a retention policy would be reflected under this option. Where the recipient is a public fora, this is the appropriate retention policy.

[40]	retention	=	"<RETENTION>" retentionvalue *extension "</RETENTION>"
[41]	retentionvalue	=	"<no-retention/>" | ; not retained "<stated-purpose/>" | ; for the stated purpose "<legal-requirement/>" | ; stated purpose by law "<indefinitely/>" | ; indeterminated period of time "<business-practices/>" ; by business practices

3.3.6 The DATA-GROUP and DATA elements

Each STATEMENT element MUST contain at least one DATA-GROUP element that contains one or more DATA elements. DATA elements are used to describe the type of data that a site collects.

<DATA-GROUP>

describes the data to be transferred or inferred

base

base URI ([URI]) for URI references present in ref attributes. When this attribute is omitted, the default value is the URI of the P3P base data schema (http://www.w3.org/TR/P3P/base). When the attribute appears as an empty string (""), the base is the local document.

<DATA>

describes the data to be transferred or inferred

ref (mandatory attribute)

URI reference ([URI]), where the fragment identifier part denotes the name of a data element/set, and the URI part denotes the corresponding dataschema. In case the URI part is not present, if the DATA element is contained within a DATA-GROUP element, then the default base URI is assumed to be the URI of the base attribute. In the other cases, as usual, the default base URI is a same-document reference ([URI]).
Remember that names of data elements and sets are case-sensitive (so, for example, user.home is different from USER.HOME or User.Home).

optional

indicates whether or not the site requires visitors to submit this data element; "no" indicates that the data element is required, while "yes" indicates that the data element is not required. The default is "no". The optional attribute is used only in policies (not in dataschema definitions).

Note that user agents should be cautious about using the optional attribute in automated decision-making. If the optional attribute is associated with a data element directly controlled by the user agent (such as the HTTP referer header or cookies), the user agent should make sure that this data is not transmitted to web sites at which a data element is optional if the site's policy would not match a user's preferences if the data element was required. Likewise, for data elements that users typically type into forms,  user agents should alert users when a site's practices about optional data do not match their preferences.

DATA elements can contain the actual data (as already seen in the case of the ENTITY element), and can contain related category information.

[42]	data-group	=	"<DATA-GROUP" [" base=" quoted-URI] ">" 1*dataref *extension "</DATA-GROUP>"
[43]	dataref	=	`<DATA" ref="` URI-reference `"` [" optional=" `"` ("yes"|"no") `"`] ">" [categories] ; the categories of the data element. [PCDATA] ; the eventual value of the data element "</DATA>"
Here, URI-reference is defined as in [URI].

For example, to reference the user's home address city, all the elements of the data set user.business-info and (optionally) all the elements of the data set user.home-info.telecom, the service would send the following references inside a P3P policy:

<DATA-GROUP>
<DATA ref="#user.home-info.city"/>
<DATA ref="#user.home-info.telecom" optional="yes"/>
<DATA ref="#user.business-info"/>
</DATA-GROUP>

When the actual value of the data is known, it can be expressed inside the DATA element. For example, as seen in the example policies:

 <ENTITY>
  <DATA-GROUP>
   <DATA ref="#business.name">CatalogExample</DATA>
   <DATA ref="#business.contact-info.postal.street">4000 Lincoln Ave.</DATA>
...

3.4 Categories

Categories are elements inside data elements that provide hints to users and user agents as to the intended uses of the data. Categories are vital to making P3P user agents easier to implement and use. Note that categories are not data elements: they just allow users to express more generalized preferences and rules over the exchange of their data.

The following elements are used to denote data categories:

[44]	categories	=	"<CATEGORIES>" 1*category "</CATEGORIES>"
[45]	category	=	"<physical/>" | ; Physical Contact Information "<online/>" | ; Online Contact Information "<uniqueid/>" | ; Unique Identifiers "<purchase/>" | ; Purchase Information "<financial/>" | ; Financial Information "<computer/>" | ; Computer Information "<navigation/>" | ; Navigation and Click-stream Data "<interactive/>" | ; Interactive Data "<demographic/>" | ; Demographic and Socioeconomic Data "<content/>" | ; Content "<state/>" | ; State Management Mechanisms "<political/>" | ; Political Information "<health/>" | ; Health Information "<preference/>" | ; Preference Data "<government/> | ; Government-issued Identifiers "<other>" PCDATA "</other>" ; Other

<physical/>

Physical Contact Information: Information that allows an individual to be contacted or located in the physical world -- such as telephone number or address.

<online/>

Online Contact Information: Information that allows an individual to be contacted or located on the Internet -- such as email. Often, this information is independent of the specific computer used to access the network. (See the category "Computer Information")

<uniqueid/>

Unique Identifiers: Non-financial identifiers, excluding government-issued identifiers, issued for purposes of consistently identifying the individual. These include identifiers issued by a web site or service.

<purchase/>

Purchase Information: Information actively generated by the purchase of a product or service, including information about the method of payment.

<financial/>

Financial Information: Information about an individual's finances including account status and activity information such as account balance, payment or overdraft history, and information about an individual's purchase or use of financial instruments including credit or debit card information. Information about a discrete purchase by an individual, as described in "Purchase Information," alone does not come under the definition of "Financial Information."

<computer/>

Computer Information: Information about the computer system that the individual is using to access the network -- such as the IP number, domain name, browser type or operating system.

<navigation/>

Navigation and Click-stream Data: Data passively generated by browsing the Web site -- such as which pages are visited, and how long users stay on each page.

<interactive/>

Interactive Data: Data actively generated from or reflecting explicit interactions with a service provider through its site -- such as queries to a search engine, or logs of account activity.

<demographic/>

Demographic and Socioeconomic Data: Data about an individual's characteristics -- such as gender, age, and income.

<content/>

Content : The words and expressions contained in the body of a communication -- such as the text of email, bulletin board postings, or chat room communications.

<state/>

State Management Mechanisms: Mechanisms for maintaining a stateful session with a user or automatically identifying users who have visited a particular site or accessed particular content previously -- such as HTTP cookies.

<political/>

Political Information: Membership in or affiliation with groups such as religious organizations, trade unions, professional associations, political parties, etc.

<health/>

Health Information: information about an individual's physical or mental health, sexual orientation, use or inquiry into health care services or products, and purchase of health care services or products.

<preference/>

Preference Data: Data about an individual's likes and dislikes -- such as favorite color or musical tastes.

<location/>

Location Data: Information that can be used to identify an individual's current physical location and track them as their location changes -- such as GPS position data.

<government/>

Government-issued Identifiers: Identifiers issued by a government for purposes of consistently identifying the individual.

<other> string </other>

Other: Other types of data not captured by the above definitions. (A human readable explanation should be provided in these instances, between the <other> and the </other> tags.)

The Computer, Navigation, Interactive and Content categories can be distinguished as follows. The Computer category includes information about the user's computer including IP address and software configuration. Navigation data describes actual user behavior related to browsing. When an IP address is stored in a log file with information related to browsing activity, both the Computer category and the Navigation category should be used. Interactive Data is data actively solicited to provide some useful service at a site beyond browsing. Content is information exchanged on a site for the purposes of communication.

The Other category should be used only when data is requested that does not fit into any other category.

P3P uses categories to give users and user agents additional hints as to what type of information is requested from a service. While most data in the Base Data Schema is in a known category (or a set of known categories), some data elements can be in a number of different categories, depending on the situation. The former are called fixed-category data elements (or "fixed data elements" for short), the latter variable-category data elements ("variable data elements"). Both types of elements are briefly described in the two sections below.

3.5 Extension Mechanism

P3P provides a flexible and powerful mechanism to extend its syntax and semantics using one element: EXTENSION. This element is used to indicate portions of the policy which belong to an extension. The meaning of the data within the EXTENSION element is defined by the extension itself.

<EXTENSION>

describes an extension to the syntax

optional

This attribute determines if the extension is mandatory or optional. A mandatory extension is indicated by giving the optional attribute a value of no. A mandatory extension to the P3P syntax means that applications that do not understand this extension cannot understand the meaning of the whole policy (or dataschema). An optional extension, indicated by giving the optional attribute a value of yes, means that applications that do not understand this extension can safely ignore the contents of the EXTENSION element, and proceed to process the whole policy (or dataschema) as usual. The optional attribute is not required; its default value is yes.

extension

=

"<EXTENSION" [" optional=" `"` ("yes"|"no") `"`] ">" PCDATA "</EXTENSION>"

For example, if www.catalog.example.com would like to add to P3P a feature to indicate that a certain set of data elements were only to be collected from users living in the United States, Canada, or Mexico, it could add a mandatory extension like this:

<DATA-GROUP>
...     
<EXTENSION>
<COLLECTION-GEOGRAPHY type="include" xmlns="http://www.catalog.example.com/P3P/region">
<USA/><Canada/><Mexico/>
</COLLECTION-GEOGRAPHY>
</EXTENSION>
</DATA-GROUP> 

On the other hand, if www.catalog.example.com would like to add an extension stating what country the server is in, an optional extension might be more appropriate, such as the following:

<POLICY>
<EXTENSION optional="yes">
<ORIGIN xmlns="http://www.catalog.example.com/P3P/origin" country="USA"/>
</EXTENSION>
...
</POLICY> 

The xmlns attribute is significant since it specifies the namespace for interpreting the names of elements and attributes used in the extension. Note that, as specified in [XML-Name], the namespace URI is just intended to be a unique identifier for the XML entities used by the extension. Nevertheless, service providers MAY provide a page with a description of the extension at the corresponding URI.

3.6 APPEL Processing

APPEL ([APPEL]) is a privacy preferences exchange language that can be used to conveniently express an automatic set of behaviours that the user agent should take when processing a privacy policy. User agents MUST be able to import and process APPEL rules and SHOULD be able to export APPEL rules. Note that these requirements do not necessarily imply that APPEL must be the only rule processing tool of the user agent, or that a user agent's power in dealing with policies must be limited to APPEL's expressivity.

4. Data Schemas

P3P has the ability to define data schemas to provide a common way for services and user agents to refer to data elements. A data schema describes specific data elements, which may be grouped into hierarchical data sets.

In order to provide multilingual support for data schema files, a server can supply the right alternative based on the HTTP Accept-Language header.

Services may declare and use data elements by creating a data schema and referencing it in a policy using the DATA element. P3P comes with a standard data schema, the P3P Base Data Schema, that defines a wide variety of commonly used data elements.

Data elements often come in groups with certain common elements: thus, P3P also allows structures to be defined. A structure is a collection of specified data elements. New structures can be defined, and P3P also provides built-in basic data structures, which can be conveniently reused by other new schemas.

The <DATASCHEMA> element contains references to the new data elements.

[47]

dataschema

=

"<DATASCHEMA" [` xmlns="http://www.w3.org/2000/09/15/P3Pv1"`] ">" *(datadef|datastruct|extension) "</DATASCHEMA>"

Data schemas can be embedded in a policy, or expressed as a stand-alone XML file. In the second case, the appropriate XML namespace attribute xmlns MUST be used to indicate this is a P3P data schema file:

<DATASCHEMA xmlns="http://www.w3.org/2000/09/15/P3Pv1">
<DATA-STRUCT ... />
...
<DATA-DEF ... />
</DATASCHEMA>

4.1 The DATA-DEF and DATA-STRUCT elements

<DATA-DEF> and <DATA-STRUCT>

Define a data element or a data structure, respectively.

The following attributes are common to these two elements:

name (mandatory attribute)

Indicates the name of the data element or data structure. Remember that names of data element and data structures are case-sensitive, so, for example, user.home is different from USER.HOME or User.Home. Furthermore, in names of data elements and structures no number character can appear immediately following a dot.

structref

URI reference ([URI]), where the fragment identifier part denotes the structure, and the URI part denotes the corresponding dataschema where it is defined. The default base URI is a same-document reference ([URI]). Data elements or data structures without a structref attribute (and, so, without an associated structure) are called unstructured.

short-description

a string denoting the short display name of the data element or structure, no more than 255 characters.

The DATA-DEF and DATA-STRUCT elements can also contain a long description of the data element or structure, using the LONG-DESCRIPTION element.

[48]	datadef	=	"<DATA-DEF name=" quotedstring [` structref="` URI-reference `"`] [" short-description=" quotedstring] ">" [categories] ; the categories of the data element. [longdescription] ; the long description of the data element "</DATA-DEF>"
[49]	datastruct	=	"<DATA-STRUCT name=" quotedstring [` structref="` URI-reference `"`] [" short-description=" quotedstring] ">" [categories] ; the categories of the Data Structure. [longdescription] ; the long description of the Data Structure "</DATA-STRUCT>"
Here, URI-reference is defined as in [URI].

Data elements can be structured, much like in common programming languages: structures are hierarchical (tree-like) descriptions of data elements: this hierarchical description is performed in the name attribute using a dot (".") character as separator.

For example, the company HyperSpeedExample might want to describe the features of a vehicle, using a structure called vehicle that includes features like a vehicle's model (vehicle.model), color (vehicle.color), year of manifacture (vehicle.built.year), price (vehicle.price ).

If HyperspeedExample also wants to include in the definition of a vehicle the location of manifacture, it could add other fields to the structure with all the relevant data like country, street address, postal code, and so on. But, each part of a structure can use other structures as well: structures can be composed. In this case, the P3P Base Data Schema (which provides built-in definitions of widely used structures and data elements) already provides a structure postal, describing all the postal information of a location. So, the final definition of the structure vehicle is

vehicle.model (unstructured)
vehicle.color (unstructured)
vehicle.built.year (unstructured)
vehicle.price (unstructured)
vehicle.built.where (with basic structure postal)

The basic structure postal has descriptions of the form postal.street, postal.city, and so on. Since we have applied the structure postal to vehicle.built.where, it means that we can access the street and city of a vehicle using the descriptions vehicle.built.where.street and vehicle.built.where.city respectively. So, applying a structure (in this case, postal) means we can build very complex descriptions in a modular way.

As said, structures do not contain data elements, they are just abstract descriptions: we can use them to rapidly build structured collections of data elements. Going on with the example, HyperSpeedExample needs this abstract description of the features of a vehicle because it wants to actually exchange data about cars and motorcycles. So, it could define two data elements called car and motorcycle, both with the above structure vehicle.

This description of the data elements (actual data elements plus, if the case, the structures needed to describe them) is encoded in XML using a dataschema. In the HyperSpeedExample case, it would be something like:

<DATASCHEMA xmlns="http://www.w3.org/2000/09/15/P3Pv1">
<DATA-STRUCT name="vehicle.model" 
    short-description="Model">
    <CATEGORIES><preference/></CATEGORIES>
</DATA-STRUCT>
<DATA-STRUCT name="vehicle.color"
    short-description="Color">
    <CATEGORIES><preference/></CATEGORIES>
</DATA-STRUCT>
<DATA-STRUCT name="vehicle.built.year" 
    short-description="Construction Year">
    <CATEGORIES><preference/></CATEGORIES>
</DATA-STRUCT>
<DATA-STRUCT name="vehicle.built.where" 
    structref="http://www.w3.org/TR/P3P/base#postal"
    short-description="Construction Place">
    <CATEGORIES><preference/></CATEGORIES>
</DATA-STRUCT>
<DATA-DEF name="car" structref="#vehicle"/>
<DATA-DEF name="motorcycle" structref="#vehicle"/>
</DATASCHEMA>

Continuing with the example, in order to reference a car model and construction year, Hyperspeed or any other service could send the following references inside a P3P policy:

<DATA-GROUP>
  <!-- First, the "car.model" data element, whose definition is in the data schema
       at http://www.HyperSpeed.example.com/models-schema
    -->
<DATA ref="http://www.HyperSpeed.example.com/models-schema#car.model"/>

  <!-- And second, the "car.built.year" data element, whose definition is the data schema
       at http://www.HyperSpeed.example.com/models-schema
    -->
<DATA ref="http://www.HyperSpeed.example.com/models-schema#car.built.year"/>
</DATA-GROUP>

As structures can also carry category information, in the above references both of the data elements are of category <preference/>, since this is the category specified in the vehicle structures for the attributes model and vehicle.

Using the base attribute, the above references can be written in an even more compact way:

<DATA-GROUP base="http://www.HyperSpeed.example.com/models-schema">
    <DATA ref="#car.model"/>
    <DATA ref="#car.built.year"/>
</DATA-GROUP>

Alternatively, the dataschema could be embedded directly into a policy file. In this case, the policy file could look like:

<POLICY xmlns="http://www.w3.org/2000/09/15/P3Pv1" ... >
<!-- Here the embedded dataschema begins -->
<DATASCHEMA>
<DATA-STRUCT name="vehicle.model" 
    short-description="Model">
    <CATEGORIES><preference/></CATEGORIES>
</DATA-STRUCT>
<DATA-STRUCT name="vehicle.color" 
    short-description="Color">
    <CATEGORIES><preference/></CATEGORIES>
</DATA-STRUCT>
<DATA-STRUCT name="vehicle.built.year" 
    short-description="Construction Year"">
    <CATEGORIES><preference/></CATEGORIES>
</DATA-STRUCT>
<DATA-STRUCT name="vehicle.built.where" 
    structref="http://www.w3.org/TR/P3P/base#postal"
    short-description="Construction Place">
    <CATEGORIES><preference/></CATEGORIES>
</DATA-STRUCT>
<DATA-DEF name="car" structref="#vehicle"/>
<DATA-DEF name="motorcycle" structref="#vehicle"/>
</DATASCHEMA>
<!-- Now the policy begins -->
...
<DATA-GROUP base="">
<DATA ref="#car.model"/>
<DATA ref="#car.built.year"/>
</DATA-GROUP>
...
</POLICY>

Data elements and structures can be classified according to whether or not they are in some fixed category (using the category element). Schema designers can use this attribute within their schema definitions to define an almost-invariable category for each element. Once defined, this value cannot be changed when referencing such elements from within user preferences and P3P policies, but it can be changed in other schema definitions (in the vehicle example above we redefine as preference the category for the vehicle.built.where structure, while the postal structure, defined in the Base Data Schema, has the physical and demographic categories).

If the CATEGORIES element is not present (so, leaving the category undefined), it MUST be explicitly listed in each P3P policy referencing such elements. Users can have different preferences depending on different category values for the same element. And in the case of undefined categories within data structures, other schema definitions can explicitly set categories in derived elements (otherwise the original definition overrides any value in the derived schema).

Note that the data element names specified in the base data schema or in extension data schemas may be used for purposes other than P3P policies. For example, web sites may use these names to label HTML form fields. By referring to data the same way in P3P policies and forms, automated form-filling tools can be better integrated with P3P user agents.

4.2 Persistence of Dataschemas

An essential requirement on dataschemas is the persistence of dataschemas: dataschemas that can be fetched at a certain URI can only be changed by extending the dataschema in a backward-compatible way (that is to say, changing the dataschema does not change the meaning of any policy using that schema). This way, the URI of a policy acts in a sense like a unique identifier for the data elements and structures contained therein: any dataschema that is not backward-compatible must therefore use a new different URI.

Note that a useful application of the persistence of dataschema is given for example in the case of multi-lingual sites: multiple language versions (translations) of the same dataschema can be offered by the server, using the HTTP "Content-Language" response header field to properly indicate that a particular language has been used for the dataschema.

4.3 Basic Data Structures

The Basic Data Structures are structures used by the P3P Base Data Schema (and possibly, due to their basic nature, they should be reused as much as possible by other different data schemas). All P3P-compliant user agent implementations MUST be aware of the Basic Data Structures. Each table below specifies the elements of a basic data structure, the categories associated, their structures, and the display names shown to users. More than one category may be associated with a fixed data element. However, each base data element is assigned to only one category whenever possible. Data schema designers are recommended to do the same.

4.3.1 Dates

The date structure specifies a date. Since date information can be used in different ways, depending on the context, all date information is tagged as being of "variable" category. Schema definitions have to explicitly set the corresponding category in the element referencing this data structure. For example, soliciting the birthday of a user might be "Demographic and Socioeconomic Data", while the expiration date of a credit card belongs to the "Purchase Information" category.

date	Category	Structure	Short display name
ymd.year	(variable-category)	unstructured	Year
ymd.month	(variable-category)	unstructured	Month
ymd.day	(variable-category)	unstructured	Day
hms.hour	(variable-category)	unstructured	Hour
hms.minute	(variable-category)	unstructured	Minute
hms.second	(variable-category)	unstructured	Second
fractionsecond	(variable-category)	unstructured	Fraction of Second
timezone	(variable-category)	unstructured	Time Zone

The "time zone" information is for example described in the time standard [ISO8601]. Note that "date.ymd" and "date.hms" can be used to fast reference the year/month/day and hour/minutes/seconds blocks respectively.

4.3.2 Names

The personname structure specifies information about the naming of a person.

personname	Category	Structure	Short display name
prefix	Demographic and Socioeconomic Data	unstructured	Name Prefix
given	Physical Contact Information	unstructured	Given Name (First Name)
family	Physical Contact Information	unstructured	Family Name (Last Name)
middle	Physical Contact Information	unstructured	Middle Name
suffix	Demographic and Socioeconomic Data	unstructured	Name Suffix
nickname	Demographic and Socioeconomic Data	unstructured	Nickname

4.4.3 Certificates

The certificate structure is used to specify identity certificates (like, for example, X.509).

certificate	Category	Structure	Short display name
key	Unique Identifiers	unstructured	Certificate Key
format	Unique Identifiers	unstructured	Certificate Format

The "format" field is used to represent the information of an IANA registered public key or authentication certificate format, while the "key" field is used to represent the corresponding certificate key.

4.3.4 Telephones

The telephonenum structure specifies the characteristics of a telephone number.

telephonenum	Category	Structure	Short display name
intcode	Physical Contact Information	unstructured	International Telephone code
loccode	Physical Contact Information	unstructured	Local Telephone Area code
number	Physical Contact Information	unstructured	Telephone Number
ext	Physical Contact Information	unstructured	Telephone Extension
comment	Physical Contact Information	unstructured	Telephone Optional Comments

4.3.5 Contact Information

The contact structure is used to specify contact information. Services can specify precisely which set of data they need, postal, telecommunication, or online address information.

contact	Category	Structure	Short display name
postal	Physical Contact Information, Demographic and Socioeconomic Data	postal	Postal Address Information
telecom	Physical Contact Information	telecom	Telecommunications Information
online	Online Contact Information	online	Online Address Information

4.3.5.1 Postal

The postal structure specifies a postal mailing address.

postal	Category	Structure	Short display name
name	Physical Contact Information, Demographic and Socioeconomic Data	personname	Name
street	Physical Contact Information	unstructured	Street Address
city	Physical Contact Information	unstructured	City
stateprov	Physical Contact Information	unstructured	State or Province
postalcode	Demographic and Socioeconomic Data	unstructured	Postal code
country	Demographic and Socioeconomic Data	unstructured	Country Name
organization	Physical Contact Information, Demographic and Socioeconomic Data	unstructured	Organization Name

The "country" field represents the information of the name of the country (for example, one among the countries listed in [ISO3166]).

4.4.5.2 Telecommunication

The telecom structure specifies telecommunication information about a person.

telecom	Category	Structure	Short display name
telephone	Physical Contact Information	telephonenum	Telephone number
fax	Physical Contact Information	telephonenum	Fax number
mobile	Physical Contact Information	telephonenum	Mobile Telephone number
pager	Physical Contact Information	telephonenum	Pager number

4.3.5.3 Online

The online structure specifies online information about a person.

online	Category	Structure	Short display name
email	Online Contact Information	unstructured	Email Address
uri	Online Contact Information	unstructured	Home Page Address

4.3.6 Access Logs and Internet Addresses

Two structures used for representing forms of Internet addresses are provided. The uri structure covers Universal Resource Identifiers (URI), which are defined in more detail in [URI]. The ipaddr structure represents IP addresses and Domain Name System (DNS) hostnames.

4.3.6.1 URI

The authority of a URI is defined as the authority component in [URI].  The stem of a URI is defined as the information contained in the portion of the URI up to (and including) the first '?' character in the URI, and the querystring is the information contained in the portion of the URI after the first '?' character. For URIs which do not contain a '?' character, the stem is the entire URI, and the querystring is empty.

Since URI information can be used in different ways, depending on the context, all the fields in the uri structure are tagged as being of "variable" category. Schema definitions MUST explicitly set the corresponding category in the element referencing this data structure.

4.3.6.2 ipaddr

The ipaddr structure represents the hostname and IP address of a system.

ipaddr	Category	Structure	Short display name
hostname	Unique Identifiers	unstructured	Complete host and domain name
partialhostname	Demographic	unstructured	Partial hostname
fullip	Unique Identifiers	unstructured	Full IP address
partialip	Demographic	unstructured	Partial IP address

The hostname element is used to represent collection of either the simple hostname of a system, or the full hostname including domain name. The partialhostname element represents the information of a fully-qualified hostname which has had at least the host portion removed from the hostname. In other words, everything up to the first '.' in the fully-qualified hostname MUST be removed for an address to quality as a "partial hostname".

The fullip element represents the information of a full IP version 4 or IP version 6 address. The partialip element represents an IP version 4 address (only - not a version 6 address) which has had at least the last 7 bits of information removed. This removal MUST be done by replacing those bits with a fixed pattern for all visitors (for example, all 0's or all 1's).

Certain Web sites are known to make use not of the visitor's entire IP address or hostname, but rather make use of a reduced form of that information. By collecting only a subset of the address information, the site visitor is given some measure of anonymity. It is certainly not the intent of this specification to claim that these "stripped" IP addresses or hostnames are impossible to associate with an individual user, but rather that it is significantly more difficult to do so. Sites which perform this data reduction MAY wish to declare this practice in order to more-accurately reflect their practices.

4.3.6.3 Access Log Information

The loginfo structure is used to represent information typically stored in Web-server access logs.

loginfo	Category	Structure	Short display name
uri	Navigation and click-stream data	uri	URI of requested resource
timestamp	Navigation and click-stream data	date	Request timestamp
clientip	Computer Information	ipaddr	Client's IP address or hostname
other.httpmethod	Navigation and click-stream data	unstructured	HTTP request method
other.bytes	Navigation and click-stream data	unstructured	Data bytes in response
other.statuscode	Navigation and click-stream data	unstructured	Response status code

The resource in the HTTP request is captured by the uri field. The time at which the server processes the request is represented by the timestamp field. Server implementations are free to define this field as the time the request was received, the time that the server began sending the response, the time that sending the response was complete, or some other convient representation of the time the request was processed. The IP address of the client system making the request is given by the clientip field.

The other data fields represent other information commonly stored in Web server access logs. other.httpmethod is the HTTP method (such as GET, POST, etc) in the client's request. other.bytes indicates the number of bytes in the response-body sent by the server. other.statuscode is the HTTP status code on the request, such as 200, 302, or 404 (see section 6.1.1 of [HTTP1.1] for details).

4.3.6.4 Other HTTP Protocol Information

The httpinfo structure represents information carried by the HTTP protocol which is not covered by the loginfo structure.

httpinfo	Category	Structure	Short display name
referer	Navigation and click-stream data	uri	Last URI requested by the user
useragent	Computer Information	unstructured	User agent information

The useragent field represents the information in the HTTP User-Agent header (which gives information about the type and version of the user's Web browser), and/or the HTTP accept* headers.

The referer field represents the  information in the HTTP Referer header, which gives information about the previous page visited by the user. Note that this field is misspelled in exactly the same way as the corresponding HTTP header.

4.4 The Base Data Schema

All P3P-compliant user agent implementations MUST be aware of the data elements in the P3P Base Data Schema. The P3P Base Data Schema includes the definition of the basic data structures, and four data element sets: user, thirdparty, business and dynamic. The user, thirdparty and business sets include elements that users and/or businesses might provide values for, while the dynamic set includes elements that are dynamically generated in the course of a user's browsing session. User agents may support a variety of mechanisms that allow users to provide values for the elements in the user set and store them in a data repository, including mechanisms that support multiple personae. Users may choose not to provide values for these data elements.

The formal XML definition of the P3P Base Data Schema is given in Appendix 3. In the following sections, the base data elements and sets are explained one by one. The members of this Working Group expect that in the future, there will be demand for the creation of other data sets and elements. Obvious applications include catalogue, payment, and agent/system attribute schemas (an extensive set of system elements is provided for example in http://www.w3.org/TR/NOTE-agent-attributes.)

Each table below specifies a set, the elements within the set, the category associated with the element, its structure, and the display name shown to users. More than one category may be associated with a fixed data element. However, each base data element is assigned to only one category whenever possible. It is recommended that data schema designers do the same.

4.4.1 User Data

The user data set includes general information about the user.

user	Category	Structure	Short display name
name	Physical Contact Information, Demographic and Socioeconomic Data	personname	User's Name
bdate	Demographic and Socioeconomic Data	date	User's Birth Date
cert	Unique Identifiers	certificate	User's Identity Certificate
gender	Demographic and Socioeconomic Data	unstructured	User's Gender (male or female)
employer	Demographic and Socioeconomic Data	unstructured	User's Employer
department	Demographic and Socioeconomic Data	unstructured	Department or division of organization where user is employed
jobtitle	Demographic and Socioeconomic Data	unstructured	User's Job Title
home-info	Physical Contact Information, Online Contact Information, Demographic and Socioeconomic Data	contact	User's Home Contact Information
business-info	Physical Contact Information, Online Contact Information, Demographic and Socioeconomic Data	contact	User's Business Contact Information

Note, that this data set includes elements that are actually sets of data themselves. These sets are defined in the Data Structures subsection of this document. The short display name for an individual element contained within a data set is defined as the concatenation of the short display names that have been defined for the set and the element, separated by a separator appropriate for the language/script in question, e.g. a comma for English. For example, the short display name for user.home.postal.postalcode could be "User's Home Contact Information, Postal Address Information, Postal code". User agent implementations may prefer to develop their own short display names rather than using the concatenated names when displaying information for the user.

4.4.2 Third Party Data

The thirdparty data set allows users and businesses to provide values for a related third party. This can be useful whenever third party information needs to be exchanged, for example when ordering a present online that should be sent to another person, or when providing information about one's spouse or business partner. Such information could be stored in a user repository alongside with the user data set. User agents may offer to store multiple such thirdparty data sets and allow users to select the appropriate values from a list when necessary.

The thirdparty data set is identical with the user data set. See section 4.4.1 User Data for details.

4.4.3 Business Data

The business data set features a subset of user data relevant for organizations. In P3P 1.0, this data set is primarily used for declaring the policy entity, though it should also be applicable to business-to-business interactions.

business	Category	Structure	Short display name
name	Demographic and Socioeconomic Data	unstructured	Organization Name
department	Demographic and Socioeconomic Data	unstructured	Department or division of organization
cert	Unique Identifiers	certificate	Organizantion Identity Certificate
contact-info	Physical Contact Information, Online Contact Information, Demographic and Socioeconomic Data	contact	Contact Information for the Organization

4.4.4 Dynamic Data

In some cases, there is a need to specify data elements that do not have fixed values that a user might type in or store in a repository. In the P3P Base Data Schema, all such elements are grouped under the dynamic data set. Sites may refer to the types of data they collect using the dynamic data set only, rather than enumerating all of the specific data elements.

dynamic	Category	Structure	Short display name
clickstream	Navigation and Click-stream Data, Computer Information	loginfo	Click-stream information
http	Navigation and Click-stream Data, Computer Information	httpinfo	HTTP protocol information
cookies	(variable-category)	unstructured	Use of HTTP cookies
miscdata	(variable-category)	unstructured	Miscellaneous non-base data schema information
searchtext	Interactive Data	unstructured	Search terms
interactionrecord	Interactive Data	unstructured	Server stores the transaction history

These elements are often implicit in navigation or Web interactions. They should be used with categories to describe the type of information collected through these methods. A brief description of each element follows.

The clickstream element is expected to apply to practically all Web sites. It represents the combination of information typically found in Web server access logs: the IP address or hostname of the user's computer, the URI of the resource requested, the time the request was made, the HTTP method used in the request, the size of the response, and the HTTP status code in the response. Web sites that collect standard server access logs can use this data element to describe how that data will be used, as well as this element sites which do URI path analysis.

Web sites that collect only some of the data elements listed for the clickstream element MAY choose to list those specific elements rather than the entire dynamic.clickstream element. This allows sites with more limited data-collection practices to accurately present those practices to their visitors.

The http element contains additional information contained in the HTTP protocol. See the definition of the httpinfo structure for descriptions of specific elements. Sites MAY use the dynamic.http field as a shorthand to cover all the elements in the httpinfo structure if they wish, or they MAY reference the specific elements in the httpinfo structure.

cookies should be used whenever HTTP cookies are set or retrieved by a site. Please note that cookies is a variable data element and requires the explicit declaration of usage categories in a policy.

The miscdata element references information collected by the service that the service does not reference using a specific data element. Categories have to be used to better describe these data: sites MUST reference a separate miscdata element in their policies for each category of miscellaneous data they collect.

searchtext is a specific type of solicitation used for searching and indexing sites. For example, if the only fields on a search engine page are search fields, the site only needs to disclose that data element.

The interactionrecord element should be used if the server is keeping track of the interaction it has with the user (i.e. information other than clickstream data, for example account transactions, etc).

4.5 Categories and Data Elements/Structures

4.5.1 Fixed-Category Data Elements/Structures

Most of the elements in the base data schema are so called "fixed" data elements: they belong to one or at most two category classes. By assigning a category invariably to elements or structures in the base data schema, services and users are able to refer to entire groups of elements simply by referencing the corresponding category. For example, using [APPEL], the privacy preferences exchange language, users can write rules that warn them when they visit a site that collects any data element in a certain category.

When creating data schemas for fixed data elements, schema creators have to explicitly enumerate the categories that these element belong to. For example:

<DATA-STRUCT name="postal.street"     structref="#text"
          short-description="Street Address">
<CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

If an element or structure belongs to multiple categories, multiple elements referencing the appropriate categories can be used. For example, the following piece of XML can be used to declare that the data elements in user.name have both category "physical" and "demographic":

<DATA-STRUCT name="user.name"     structref="#personname"
          short-description="User's Name">
<CATEGORIES><physical/><demographic/></CATEGORIES>
</DATA-STRUCT>

Please note that the category classes of fixed data elements/structures can not be overridden, for example by writing rules or policies that assign a different category to a known fixed base data element. User Agents MUST ignore such categories and instead use the original category (or set of categories) listed in the schema definition. User Agents MAY preferably alert the user that a fixed data element is used together with a non-standard category class.

4.5.2 Variable-Category Data Elements/Structures

Not all data elements/structures in the base data schema belong to a pre-determined category class. Some can contain information from a range of categories, depending on a particular situation. Such elements/structures are called variable-category data elements/structures (or "variable data element/structure" for short). Although most variable data elements in the P3P Base Data Schema are combined in the dynamic element set, they can appear in any data set, even mixed with fixed-category data elements.

When creating a schema definition for such elements and/or structures, schema authors MUST NOT list an explicit category attribute, otherwise the element/structure becomes fixed. For example when specifying the "Year" Data Structure, which can take various categories depending on the situation (e.g. when used for a credit card expiration date vs. for a birth date), the following schema definition can be used:

<DATA-STRUCT name="date.ymd.year"
          short-description="Year"/>  <!-- Variable Data Structure-->

This allows new schema extensions that reference such variable-category Data Structures to assign a specific category to derived elements, depending on their usage in that extension. For example, an e-commerce schema extension could thus define a credit card expiration date as follows:

<DATA-STRUCT name="Card.ExpDate"         structref="#date.ymd"
          short-description="Card Expiration Date">
<CATEGORIES><purchase/></CATEGORIES>
</DATA-STRUCT>

Under these conditions, the variable Data Structure date is assigned a fixed category "Purchase Information" when being used for specifying a credit card expiration date.

Note that while user preferences can list such variable data elements without any additional category information (effectively expressing preferences over any usage of this element), services MUST always explicitly specify the categories that apply to the usage of a variable data element in their particular policy. This information has to appear as a category element in the corresponding DATA element listed in the policy, for example as in:

<POLICY ... >
   ...
   <DATA ref="#dynamic.cookies"><CATEGORIES><uniqueid/></CATEGORIES></DATA>
   ...
</POLICY>

where a service declares that cookies are used for identifying the user at this site (i.e. category Unique Identifiers).

If a service wants to declare a data element that is in multiple categories, it simply declares the corresponding categories (as shown in the above section):

<POLICY ... >
   ...
   <DATA ref="#dynamic.cookies"><CATEGORIES><uniqueid/><preference/></CATEGORIES></DATA>
   ...
</POLICY>

With the above declaration a service announces that it uses cookies both for identifying the user at this site and for storing user preference data. Note that for the purpose of P3P there is no difference whether this information is stored in two separate cookies or in a single one.

Finally, note that categories can be inherited as well: Categories inherit downward when a field is structured, but only into fields which have no predefined category. Therefore, we suggest we to schema authors that they do their best to insure that all applicable categories are applied to new data elements they create.

4.6 Using Data Elements

P3P offers Web sites a great deal of flexibility in how they describe the types of data they collect.

• Sites may describe data generally using the dynamic.miscdata element and the appropriate categories.
• Sites may describe data specifically using the data elements defined in the base data schema.
• Sites may describe data specifically using data elements defined in new data schemas.

And these three methods may be combined within a single policy.

By using the dynamic.miscdata element, sites can specify the types of data they collect without having to enumerate every individual data element. This may be convenient for sites that collect a lot of data or sites belonging to large organizations that want to offer a single P3P policy covering the entire organization. However, the disadvantage of this approach is that user agents will have to assume that the site might collect any data element belonging to the categories referenced by the site. So, for example, if a site's policy states that it collects dynamic.miscdata of the physical contact information category, but the only physical contact information it collects is business address, user agents will none-the-less assume that the site might also collect telephone numbers. If the site wishes to be clear that it does not collect telephone numbers or any other physical contact information other than business address, than it should disclose that it collects user.business-info.contact.postal. Furthermore, as user agents are developed with automatic form-filling capabilities, it is likely that sites that enumerate the data they collect will be able to better integrate with these tools.

By defining new data schemas, sites can precisely specify the data they collect beyond the base data set. However, if user agents are unfamiliar with the elements defined in these schemas, they will be able to provide only minimal information to the user about these new elements. The information they provide will be based on the category and display names specified for each element.

Regardless of whether a site wishes to make general or specific data disclosures, there are additional advantages to disclosing specific elements from the dynamic data set. For example, by disclosing dynamic.cookies a site can indicate that it uses cookies and explain the purpose of this use. The working group encourages user agent implementations that offer users cookie control interfaces based on this information. Likewise, user agents that by default do not send the HTTP_REFERER header, might look for the dynamic.http.referer element in P3P policies and send the header if it will be used for a purpose the user finds acceptable.

5. Appendices

Appendix 1: References (Normative)

[APPEL]

M. Langheinrich (Ed.). "A P3P Preference Exchange Language (APPEL)" World Wide Web Consortium Working Draft.

[CHARMODEL]

M. Dürst, F. Yergeau (Eds.), "Character Model for the World Wide Web ," World Wide Web Consortium Working Draft. 29 November 1999.

[HTTP1.0]

T. Berners-Lee, R. Fielding, H. Frystyk, "RFC1945 -- Hypertext Transfer Protocol -- HTTP/1.0," May 1996.

[HTTP1.1]

R. Fielding, J. Gettys, J. Mogul, H. Frystyk, L. Masinter, P. Leach, T. Berners-Lee, "RFC2616 -- Hypertext Transfer Protocol -- HTTP/1.1," June 1999. [Updates RFC2068]

[KEY]

S. Bradner. "RFC2119-- Key words for use in RFCs to Indicate Requirement Levels." March 1997.

[P3P-HEADER]

R. Lotenberg, M. Marchiori, M. Nottingham (Eds.), " W3C Platform for Privacy Preferences 1.0 (P3P1.0) HTTP Header" (also available in HTML and XML formats), to be submitted to the IETF as Internet Draft.

[URI]

T. Berners-Lee, R. Fielding, and L. Masinter. "RFC 2396 -- Uniform Resource Identifiers (URI): Generic Syntax and Semantics." August 1998. [Updates RFC1738]

[UTF-8]

F. Yergeau. "RFC2279 -- UTF-8, a transformation format of ISO 10646." January 1998.

[XML]

T. Bray, J. Paoli, C. M. Sperberg-McQueen (Eds.). "Extensible Markup Language (XML) 1.0 Specification." World Wide Web Consortium, Recommendation. 10 February 1998.

[XML-Name]

T. Bray, D. Hollander, A. Layman (Eds.). "Namespaces in XML." World Wide Web Consortium, Recommendation. 14 January 1999.

[XML-Schema1]

H. Thompson, D. Beech, M. Maloney, and N. Mendelsohn (Eds.). "XML Schema Part 1: Structures" World Wide Web Consortium Working Draft. 7 April 2000.

[XML-Schema2]

P. Biron, A. Malhotra (Eds.). "XML Schema Part 2: datatypes" World Wide Web Consortium Working Draft. 7 April 2000.

Appendix 2: References (Non-Normative)

[ABNF]

D. Crocker, P. Overel. "RFC2234 -- Augmented BNF for Syntax Specifications: ABNF," Internet Mail Consortium, Demon Internet Ltd., November 1997.

[HTML]

D. Raggett, A. Le Hors, and I. Jacobs (Eds.). "HTML 4.01 Specification" World Wide Web Consortium

[ISO3166]

"ISO3166: Codes for The Representation of Names of Countries." International Organization for Standardization.

[ISO8601]

"ISO8601: Data elements and interchange formats -- Information interchange -- Representation of dates and times." International Organization for Standardization.

[RDF]

O. Lassila and R. Swick (Eds.). "Resource Description Framework (RDF) Model and Syntax Specification." W3C Recommendation. 22 February 1999.

[UNICODE]

Unicode Consortium. "The Unicode Standard"

Appendix 3: The P3P Base Data Schema Definition (Normative)

The data schema corresponding to the P3P base data schema follows for easy reference. The schema is also present as a separate file at the URI http://www.w3.org/TR/P3P/base .

<DATASCHEMA xmlns="http://www.w3.org/2000/09/15/P3Pv1">
<!-- ********** Base Data Structures ********** -->

<!-- "date" Data Structure -->
<DATA-STRUCT name="date.ymd.year"
    short-description="Year"/>

<DATA-STRUCT name="date.ymd.month"
    short-description="Month"/>

<DATA-STRUCT name="date.ymd.day"
    short-description="Day"/>

<DATA-STRUCT name="date.hms.hour"
    short-description="Hour"/>

<DATA-STRUCT name="date.hms.minute"
    short-description="Minutes"/>

<DATA-STRUCT name="date.hms.second"
    short-description="Second"/>

<DATA-STRUCT name="date.fractionsecond"
    short-description="Fraction of Second"/>

<DATA-STRUCT name="date.timezone"
    short-description="Time Zone"/>

<!-- "personname" Data Structure -->
<DATA-STRUCT name="personname.prefix"
    short-description="Name Prefix">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="personname.given"
    short-description="Given Name (First Name)">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="personname.middle"
    short-description="Middle Name">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="personname.family"
    short-description="Family Name (Last Name)">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="personname.suffix"
    short-description="Name Suffix">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="personname.nickname"
    short-description="Nickname">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-STRUCT>

<!-- "certificate" Data Structure -->
<DATA-STRUCT name="certificate.key"
    short-description="Certificate key">
    <CATEGORIES><uniqueid/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="certificate.format"
    short-description="Certificate format">
    <CATEGORIES><uniqueid/></CATEGORIES>
</DATA-STRUCT>

<!-- "telephonenum" Data Structure -->
<DATA-STRUCT name="telephonenum.intcode"
    short-description="International Telephone Code">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="telephonenum.loccode"
    short-description="Local Telephone Area Code">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="telephonenum.number"
    short-description="Telephone Number">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="telephonenum.ext"
    short-description="Telephone Extension">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="telephonenum.comment"
    short-description="Telephone Optional Comments">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<!-- "postal" Data Structure -->
<DATA-STRUCT name="postal.name" struct-ref="#personname">
    <CATEGORIES><physical/><demographic/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="postal.street"
    short-description="Street Address">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="postal.city"
    short-description="City">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="postal.stateprov"
    short-description="State or Province">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="postal.postalcode"
    short-description="Postal Code">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="postal.organization"
    short-description="Organization Name">
    <CATEGORIES><physical/><demographic/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="postal.country"
    short-description="Country Name">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-STRUCT>

<!-- "telecom" Data Structure -->
<DATA-STRUCT name="telecom.telephone"
    short-description="Telephone Number"
    structref="#telephonenum">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="telecom.fax"
    short-description="Fax Number"
    structref="#telephonenum">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="telecom.mobile"
    short-description="Mobile Telephone Number"
    structref="#telephonenum">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="telecom.pager"
    short-description="Pager Number"
    structref="#telephonenum">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<!-- "online" Data Structure -->
<DATA-STRUCT name="online.email"
    short-description="Email Address">
    <CATEGORIES><online/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="online.uri"
    short-description="Home Page Address">
    <CATEGORIES><online/></CATEGORIES>
</DATA-STRUCT>

<!-- "contact" Data Structure -->
<DATA-STRUCT name="contact.postal"
    short-description="Postal Address Information"
    structref="#postal">
    <CATEGORIES><physical/><demographic/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="contact.telecom"
    short-description="Telecommunications Information"
    structref="#telecom">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="contact.online"
    short-description="Online Address Information"
    structref="#online">
    <CATEGORIES><online/></CATEGORIES>
</DATA-STRUCT>

<!-- "uri" Data Structure -->
<DATA-STRUCT name="uri.authority"
    short-description="URI authority"/>

<DATA-STRUCT name="uri.stem"
    short-description="URI stem"/>

<DATA-STRUCT name="uri.querystring"
    short-description="Query-string portion of URI"/>

<!-- "ipaddr" Data Structure -->
<DATA-STRUCT name="ipaddr.hostname"
    short-description="Complete host and domain name">
    <CATEGORIES><uniqueid/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="ipaddr.partialhostname"
    short-description="Partial hostname">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="ipaddr.fullip"
    short-description="Full IP address">
    <CATEGORIES><uniqueid/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="ipaddr.partialip"
    short-description="Partial IP address">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-STRUCT>

<!-- "loginfo" Data Structure -->
<DATA-STRUCT name="loginfo.uri"
    short-description="URI of requested resource"
    structref="#uri">
    <CATEGORIES><navigation/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="loginfo.timestamp"
    short-description="Request timestamp"
    structref="#date">
    <CATEGORIES><navigation/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="loginfo.clientip"
    short-description="Client's IP address or hostname"
    structref="#ipaddr">
    <CATEGORIES><computer/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="loginfo.other.httpmethod"
    short-description="HTTP request method">
    <CATEGORIES><navigation/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="loginfo.other.bytes"
    short-description="Data bytes in response">
    <CATEGORIES><navigation/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="loginfo.other.statuscode"
    short-description="Response status code">
    <CATEGORIES><navigation/></CATEGORIES>
</DATA-STRUCT>

<!-- "httpinfo" Data Structure -->
<DATA-STRUCT name="httpinfo.referer"
    short-description="Last URI requested by the user"
    structref="#uri">
    <CATEGORIES><navigation/></CATEGORIES>
</DATA-STRUCT>

<DATA-STRUCT name="httpinfo.useragent"
    short-description="User agent information">
    <CATEGORIES><computer/></CATEGORIES>
</DATA-STRUCT>

<!-- ********** Base Data Schemas ********** -->

<!-- "dynamic" Data Schema -->
<DATA-DEF name="dynamic.clickstream"
    short-description="Click-stream information"
    structref="#loginfo">
    <CATEGORIES><navigation/><computer/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="dynamic.cookies"
    short-description="HTTP Cookies">
</DATA-DEF>

<DATA-DEF name="dynamic.http"
    short-description="HTTP protocol information"
    structref="#httpinfo">
    <CATEGORIES><navigation/><computer/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="dynamic.miscdata"
    short-description="Other information"/>

<DATA-DEF name="dynamic.searchtext"
    short-description="Search terms">
    <CATEGORIES><interactive/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="dynamic.interactionrecord"
    short-description="Transaction history">
    <CATEGORIES><interactive/></CATEGORIES>
</DATA-DEF>

<!-- "user" Data Schema -->
<DATA-DEF name="user.name"
    short-description="User's Name"
    structref="#personname">
    <CATEGORIES><physical/><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="user.bdate"
    short-description="User's Birth Date"
    structref="#date">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="user.cert"
    short-description="User's Identity certificate"
    structref="#certificate">
    <CATEGORIES><uniqueid/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="user.gender"
    short-description="User's Gender">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="user.jobtitle"
    short-description="User's Job Title">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="user.home-info"
    short-description="User's Home Contact Information"
    structref="#contact">
    <CATEGORIES><physical/><online/><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="user.business-info"
    short-description="User's Business Contact Information"
    structref="#contact">
    <CATEGORIES><physical/><online/><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="user.employer"
    short-description="Name of User's Employer">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="user.department"
    short-description="Department or division of organization where user is employed">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-DEF>

<!-- "thirdparty" Data Schema -->
<DATA-DEF name="thirdparty.name"
    short-description="Third Party's Name"
    structref="#personname">
    <CATEGORIES><physical/><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="thirdparty.bdate"
    short-description="Third Party's Birth Date"
    structref="#date">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="thirdparty.cert"
    short-description="Third Party's Identity certificate"
    structref="#certificate">
    <CATEGORIES><uniqueid/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="thirdparty.gender"
    short-description="Third Party's Gender">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="thirdparty.jobtitle"
    short-description="Third Party's Job Title">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="thirdparty.home-info"
    short-description="Third Party's Home Contact Information"
    structref="#contact">
    <CATEGORIES><physical/><online/><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="thirdparty.business-info"
    short-description="Third Party's Business Contact Information"
    structref="#contact">
    <CATEGORIES><physical/><online/><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="thirdparty.employer"
    short-description="Name of Third Party's Employer">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="thirdparty.department"
    short-description="Department or division of organization where third party is employed">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-DEF>

<!-- "business" Data Schema -->
<DATA-DEF name="business.name"
    short-description="Organization Name">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="business.department"
    short-description="Department or division of organization">
    <CATEGORIES><demographic/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="business.cert"
    short-description="Organization Identity certificate"
    structref="#certificate">
    <CATEGORIES><uniqueid/></CATEGORIES>
</DATA-DEF>

<DATA-DEF name="business.contact-info"
    short-description="Contact Information for the Organization"
    structref="#contact">
    <CATEGORIES><physical/></CATEGORIES>
</DATA-DEF>

</DATASCHEMA>

Appendix 4: XML Schema Definition (Normative)

This appendix contains the XML Schema, both for P3P policy reference files, for P3P policy documents, and for P3P dataschema documents. An XML Schema may be used to validate the structure and datastruct values used in an instance of the schema given as an XML document. P3P policy and dataschema documents are XML documents that MUST conform to this schema. Note that this schema is based on the XML Schema working drafts [XML-Schema1][XML-Schema2], which are subject to change. The schema is also present as a separate file at the URI http://www.w3.org/2000/09/15/P3Pv1.xsd .

<?xml version='1.0'?>
<schema
  xmlns='http://www.w3.org/1999/XMLSchema'
  xmlns:p3p='http://www.w3.org/2000/09/15/P3Pv1'
  targetNamespace='http://www.w3.org/2000/09/15/P3Pv1'
  elementFormDefault='qualified'>

<!-- Basic P3P Data Type -->
 <simpleType name='yes_no' base='string'>
  <enumeration value='yes'/>
  <enumeration value='no'/>
 </simpleType>


<!-- *********** Policy Refernece *********** -->
<!-- ************** META ************** -->
 <element name='META'>
  <complexType content='mixed'>
   <element ref='p3p:POLICY-REFERENCES'/>
  </complexType>
 </element>

<!-- ******* POLICY-REFERENCES ******** -->
 <element name='POLICY-REFERENCES'>
  <complexType content='elementOnly'>
   <element ref='p3p:EXPIRY' minOccurs='0'/>
   <element ref='p3p:POLICY-REF' minOccurs='0' maxOccurs='unbounded'/>
   <element ref='p3p:POLICIES' minOccurs='0'/>
  </complexType>
 </element>

 <element name='POLICY-REF'>
  <complexType content='elementOnly'>
   <element name='INCLUDE' minOccurs='0' maxOccurs='unbounded' type='uriReference'/>
   <element name='EXCLUDE' minOccurs='0' maxOccurs='unbounded' type='uriReference'/>
   <element name='EMBEDDED-INCLUDE' minOccurs='0' maxOccurs='unbounded' type='uriReference'/>
   <element name='EMBEDDED-EXCLUDE' minOccurs='0' maxOccurs='unbounded' type='uriReference'/>
   <element name='METHOD' minOccurs='0' maxOccurs='unbounded' type='uriReference'/>
   <attribute name='about' type='uriReference' use='required'/>
  </complexType>
 </element>

<!-- ************* EXPIRY ************* -->
 <element name='EXPIRY'>
  <complexType content='empty'>
   <attribute name='max-age' type='nonNegativeInteger' use='optional'/>
   <attribute name='date' type='string' use='optional'/>
  </complexType>
 </element>

<!-- ************ POLICIES ************ -->
 <element name='POLICIES'>
  <complexType content='elementOnly'>
   <element ref='p3p:POLICY' minOccurs='0' maxOccurs='unbounded'/>
  </complexType>
 </element>


<!-- **************** Policy **************** -->
<!-- ************* POLICY ************* -->
 <element name='POLICY'>
  <complexType content='elementOnly'>
   <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
   <element ref='p3p:EXPIRY' minOccurs='0'/>
   <element ref='p3p:DATASCHEMA' minOccurs='0'/>
   <element ref='p3p:ENTITY'/>
   <element ref='p3p:ACCESS'/>
   <element ref='p3p:DISPUTES-GROUP' minOccurs='0'/>
   <element ref='p3p:STATEMENT' minOccurs='0' maxOccurs='unbounded'/>
   <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
   <attribute name='discuri' type='uriReference' use='required'/>
   <attribute name='opturi' type='uriReference' use='optional'/>
   <attribute name='name' type='ID' use='optional'/>
  </complexType>
 </element>

<!-- ************* ENTITY ************* -->
 <element name='ENTITY'>
  <complexType content='elementOnly'>
   <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
   <element ref='p3p:DATA-GROUP'/>
   <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
  </complexType>
 </element>

<!-- ************* ACCESS ************* -->
 <element name='ACCESS'>
  <complexType content='elementOnly'>
   <choice>
    <element name='nonident' type='p3p:access-value'/>
    <element name='all' type='p3p:access-value'/>
    <element name='contact_and_other' type='p3p:access-value'/>
    <element name='ident_contact' type='p3p:access-value'/>
    <element name='other_ident' type='p3p:access-value'/>
    <element name='none' type='p3p:access-value'/>
   </choice>
   <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
  </complexType>
 </element>

 <complexType name='access-value' content='empty'/>

<!-- ************ DISPUTES ************ -->
 <element name='DISPUTES-GROUP'>
  <complexType content='elementOnly'>
   <element ref='p3p:DISPUTES' maxOccurs='unbounded'/>
   <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
  </complexType>
 </element>

 <element name='DISPUTES'>
  <complexType content='elementOnly'>
   <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
   <choice minOccurs='0'>
    <sequence>
     <element ref='p3p:LONG-DESCRIPTION'/>
     <element ref='p3p:IMG' minOccurs='0'/>
     <element ref='p3p:REMEDIES' minOccurs='0'/>
     <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
    </sequence>
    <sequence>
     <element ref='p3p:IMG'/>
     <element ref='p3p:REMEDIES' minOccurs='0'/>
     <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
    </sequence>
    <sequence>
     <element ref='p3p:REMEDIES'/>
     <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
    </sequence>
   </choice>
   <attribute name='resolution-type' use='required'>
    <simpleType base='string'>
     <enumeration value='service'/>
     <enumeration value='independent'/>
     <enumeration value='court'/>
     <enumeration value='law'/>
    </simpleType>
   </attribute>
   <attribute name='service' type='uriReference' use='required'/>
   <attribute name='verification' type='string' use='optional'/>
   <attribute name='short-description' type='string' use='optional'/>
  </complexType>
 </element>

<!-- ******** LONG-DESCRIPTION ******** -->
 <element name='LONG-DESCRIPTION'>
  <simpleType base='string'/>
 </element>

<!-- ************** IMG *************** -->
 <element name='IMG'>
  <complexType content='empty'>
   <attribute name='src' type='uriReference' use='required'/>
   <attribute name='width' type='nonNegativeInteger' use='optional'/>
   <attribute name='height' type='nonNegativeInteger' use='optional'/>
   <attribute name='alt' type='string' use='required'/>
  </complexType>
 </element>

<!-- ************ REMEDIES ************ -->
 <element name='REMEDIES'>
  <complexType content='elementOnly'>
   <choice maxOccurs='unbounded'>
    <element name='correct' type='p3p:remedies-value'/>
    <element name='money' type='p3p:remedies-value'/>
    <element name='law' type='p3p:remedies-value'/>
   </choice>
   <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
  </complexType>
 </element>

 <complexType name='remedies-value' content='empty'/>

<!-- *********** STATEMENT ************ -->
 <element name='STATEMENT'>
  <complexType content='elementOnly'>
   <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
   <element name='CONSEQUENCE' minOccurs='0' type='string'/>
   <element ref='p3p:PURPOSE'/>
   <element ref='p3p:RECIPIENT'/>
   <element ref='p3p:RETENTION'/>
   <element ref='p3p:DATA-GROUP' maxOccurs='unbounded'/>
   <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
  </complexType>
 </element>

<!-- ************ PURPOSE ************* -->
 <element name='PURPOSE'>
  <complexType content='elementOnly'>
   <choice maxOccurs='unbounded'>
    <element name='current' type='p3p:purpose-value'/>
    <element name='admin' type='p3p:purpose-value'/>
    <element name='develop' type='p3p:purpose-value'/>
    <element name='customization' type='p3p:purpose-value'/>
    <element name='tailoring' type='p3p:purpose-value'/>
    <element name='pseudo-analysis' type='p3p:purpose-value'/>
    <element name='pseudo-decision' type='p3p:purpose-value'/>
    <element name='individual-analysis' type='p3p:purpose-value'/>
    <element name='individual-decision' type='p3p:purpose-value'/>
    <element name='contact' type='p3p:purpose-value'/>
    <element name='historical' type='p3p:purpose-value'/>
    <element name='telemarketing' type='p3p:purpose-value'/>
    <element name='other-purpose'>
     <complexType content='mixed'>
      <attribute name='required' use='optional' type='p3p:required-value'/>
     </complexType>
    </element>
   </choice>
   <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
  </complexType>
 </element>


 <simpleType name='required-value' base='string'>
  <enumeration value='always'/>
  <enumeration value='opt_in'/>
  <enumeration value='opt_out'/>
 </simpleType>

 <complexType name='purpose-value' content='empty'>
  <attribute name='required' use='optional' type='p3p:required-value'/>
 </complexType>

<!-- *********** RECIPIENT ************ -->
 <element name='RECIPIENT'>
  <complexType content='elementOnly'>
   <choice maxOccurs='unbounded'>
    <element name='ours'>
     <complexType content='elementOnly'>
      <element ref='p3p:recipient-description' minOccurs='0' maxOccurs='unbounded'/>
     </complexType>
    </element>
    <element name='same' type='p3p:recipient-value'/>
    <element name='other-recipient' type='p3p:recipient-value'/>
    <element name='delivery' type='p3p:recipient-value'/>
    <element name='public' type='p3p:recipient-value'/>
    <element name='unrelated' type='p3p:recipient-value'/>
   </choice>
   <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
  </complexType>
 </element>

 <complexType name='recipient-value' content='elementOnly'>
  <element ref='p3p:recipient-description' minOccurs='0' maxOccurs='unbounded'/>
  <attribute name='required' use='optional' type='p3p:required-value'/>
 </complexType>

 <element name='recipient-description' content='mixed'/>

<!-- *********** RETENTION ************ -->
 <element name='RETENTION'>
  <complexType content='elementOnly'>
   <choice>
    <element name='no-retention' type='p3p:retention-value'/>
    <element name='stated-purpose' type='p3p:retention-value'/>
    <element name='legal-requirement' type='p3p:retention-value'/>
    <element name='indefinitely' type='p3p:retention-value'/>
    <element name='business-practices' type='p3p:retention-value'/>
   </choice>
   <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
  </complexType>
 </element>

 <complexType name='retention-value' content='empty'/>

<!-- ************** DATA ************** -->
 <element name='DATA-GROUP'>
  <complexType content='elementOnly'>
   <element ref='p3p:DATA' maxOccurs='unbounded'/>
   <element ref='p3p:EXTENSION' minOccurs='0' maxOccurs='unbounded'/>
   <attribute name='base' type='uriReference' use='default' 
              value='http://www.w3.org/TR/P3P/base'/>
  </complexType>
 </element>

 <element name='DATA'>
  <complexType content='mixed'>
   <sequence minOccurs='0' maxOccurs='unbounded'>
    <element ref='p3p:CATEGORIES'/>
   </sequence>
   <attribute name='ref' type='uriReference' use='required'/>
   <attribute name='optional' use='default' value='no' type='p3p:yes_no'/>
  </complexType>
 </element>


<!-- ************** Data Schema ************* -->
<!-- *********** DATASCHEMA *********** -->
 <element name='DATASCHEMA'>
  <complexType content='elementOnly'>
   <choice minOccurs='0' maxOccurs='unbounded'>
    <element ref='p3p:DATA-DEF'/>
    <element ref='p3p:DATA-STRUCT'/>
    <element ref='p3p:EXTENSION'/>
   </choice>
  </complexType>
 </element>

 <complexType name='data-def' content='elementOnly'>
  <element ref='p3p:CATEGORIES' minOccurs='0'/>
  <element ref='p3p:LONG-DESCRIPTION' minOccurs='0'/>
  <attribute name='name' type='ID' use='required'/>
  <attribute name='structref' type='uriReference' use='optional'/>
  <attribute name='short-description' type='string' use='optional'/>
 </complexType>

 <element name='DATA-DEF' type='p3p:data-def'/>
 <element name='DATA-STRUCT' type='p3p:data-def'/>

<!-- *********** CATEGORIES *********** -->
 <element name='CATEGORIES'>
  <complexType content='elementOnly'>
   <choice maxOccurs='unbounded'>
    <element name='physical' type='p3p:categories-value'/>
    <element name='online' type='p3p:categories-value'/>
    <element name='uniqueid' type='p3p:categories-value'/>
    <element name='purchase' type='p3p:categories-value'/>
    <element name='financial' type='p3p:categories-value'/>
    <element name='computer' type='p3p:categories-value'/>
    <element name='navigation' type='p3p:categories-value'/>
    <element name='interactive' type='p3p:categories-value'/>
    <element name='demographic' type='p3p:categories-value'/>
    <element name='content' type='p3p:categories-value'/>
    <element name='state' type='p3p:categories-value'/>
    <element name='political' type='p3p:categories-value'/>
    <element name='health' type='p3p:categories-value'/>
    <element name='preference' type='p3p:categories-value'/>
    <element name='government' type='p3p:categories-value'/>
    <element name='other' type='string'/>
   </choice>
  </complexType>
 </element>

 <complexType name='categories-value' content='empty'/>

<!-- *********** EXTENSION ************ -->
 <element name='EXTENSION'>
  <complexType content='mixed'>
   <any minOccurs='0' maxOccurs='unbounded' processContents='skip'/>
   <attribute name='optional' use='default' value='yes' type='p3p:yes_no'/>
  </complexType>
 </element>

</schema>

Appendix 5: XML DTD Definition (Normative)

This appendix contains the DTD for policy documents and for dataschemas. The DTD is also present as a separate file at the URI http://www.w3.org/2000/09/15/P3Pv1.dtd .

<!-- *************** Entities *************** -->
<!ENTITY % URI "CDATA">
<!ENTITY % NUMBER "CDATA">

<!-- *********** Policy Refernece *********** -->

<!-- ************** META ************** -->
<!ELEMENT META (#PCDATA | POLICY-REFERENCES)*>

<!-- ******* POLICY-REFERENCES ******** -->
<!ELEMENT POLICY-REFERENCES (EXPIRY?, POLICY-REF*, POLICIES?)>
<!ELEMENT POLICY-REF (INCLUDE*,
    EXCLUDE*,
    EMBEDDED-INCLUDE*,
    EMBEDDED-EXCLUDE*,
    METHOD*)>
<!ATTLIST POLICY-REF 
    about %URI; #REQUIRED >

<!-- ************* EXPIRY ************* -->
<!ELEMENT EXPIRY EMPTY>
<!ATTLIST EXPIRY 
    max-age %NUMBER; #IMPLIED
    date    CDATA    #IMPLIED >

<!-- ************ POLICIES ************ -->
<!ELEMENT POLICIES (POLICY*)>

<!-- ***** INCLUDE/EXCLUDE/METHOD ***** -->
<!ELEMENT INCLUDE          (#PCDATA)>
<!ELEMENT EXCLUDE          (#PCDATA)>
<!ELEMENT EMBEDDED-INCLUDE (#PCDATA)>
<!ELEMENT EMBEDDED-EXCLUDE (#PCDATA)>
<!ELEMENT METHOD           (#PCDATA)>

<!-- **************** Policy **************** -->

<!-- ************* POLICY ************* -->
<!ELEMENT POLICY (EXTENSION*,
    EXPIRY?,
    DATASCHEMA?,
    ENTITY,
    ACCESS,
    DISPUTES-GROUP?,
    STATEMENT*,
    EXTENSION*)>
<!ATTLIST POLICY
    discuri %URI; #REQUIRED
    opturi  %URI; #IMPLIED
    name    ID    #IMPLIED >

<!-- ************* ENTITY ************* -->
<!ELEMENT ENTITY (EXTENSION*, DATA-GROUP, EXTENSION*)>

<!-- ************* ACCESS ************* -->
<!ELEMENT ACCESS ((nonident
    | all
    | contact_and_other
    | ident_contact
    | other_ident
    | none),
    EXTENSION*)>
<!ELEMENT nonident          EMPTY>
<!ELEMENT all               EMPTY>
<!ELEMENT contact_and_other EMPTY>
<!ELEMENT ident_contact     EMPTY>
<!ELEMENT other_ident       EMPTY>
<!ELEMENT none              EMPTY>

<!-- ************ DISPUTES ************ -->
<!ELEMENT DISPUTES-GROUP (DISPUTES+, EXTENSION*)>
<!ELEMENT DISPUTES (EXTENSION*,
    ( (LONG-DESCRIPTION, IMG?, REMEDIES?, EXTENSION*)
      | (IMG, REMEDIES?, EXTENSION*)
      | (REMEDIES, EXTENSION*) )?)>
<!ATTLIST DISPUTES
    resolution-type   (service | independent | court | law) #REQUIRED
    service           %URI;                                 #REQUIRED
    verification      CDATA                                 #IMPLIED 
    short-description CDATA                                 #IMPLIED >

<!-- ******** LONG-DESCRIPTION ******** -->
<!ELEMENT LONG-DESCRIPTION (#PCDATA)>

<!-- ************** IMG *************** -->
<!ELEMENT IMG EMPTY>
<!ATTLIST IMG
    src    %URI;    #REQUIRED
    width  %NUMBER; #IMPLIED
    height %NUMBER; #IMPLIED
    alt    CDATA    #REQUIRED >

<!-- ************ REMEDIES ************ -->
<!ELEMENT REMEDIES ((correct | money | law)+, EXTENSION*)>
<!ELEMENT correct EMPTY>
<!ELEMENT money   EMPTY>
<!ELEMENT law     EMPTY>

<!-- *********** STATEMENT ************ -->
<!ELEMENT STATEMENT (EXTENSION*,
    CONSEQUENCE?,
    PURPOSE,
    RECIPIENT,
    RETENTION,
    DATA-GROUP+,
    EXTENSION*)>

<!-- ********** CONSEQUENCE *********** -->
<!ELEMENT CONSEQUENCE (#PCDATA)>

<!-- ************ PURPOSE ************* -->
<!ELEMENT PURPOSE ((current
    | admin
    | develop
    | customization
    | tailoring
    | pseudo-analysis
    | pseudo-decision
    | individual-analysis
    | individual-decision
    | contact
    | historical
    | telemarketing
    | other-purpose)+,
    EXTENSION*)>

<!ENTITY % pur_att
         "required (always | opt_in | opt_out) #IMPLIED">
<!ELEMENT current             EMPTY>
<!ATTLIST current             %pur_att;>
<!ELEMENT admin               EMPTY>
<!ATTLIST admin               %pur_att;>
<!ELEMENT develop             EMPTY>
<!ATTLIST develop             %pur_att;>
<!ELEMENT customization       EMPTY>
<!ATTLIST customization       %pur_att;>
<!ELEMENT tailoring           EMPTY>
<!ATTLIST tailoring           %pur_att;>
<!ELEMENT pseudo-analysis     EMPTY>
<!ATTLIST pseudo-analysis     %pur_att;>
<!ELEMENT pseudo-decision     EMPTY>
<!ATTLIST pseudo-decition     %pur_att;>
<!ELEMENT individual-analysis EMPTY>
<!ATTLIST individual-analysis %pur_att;>
<!ELEMENT individual-decision EMPTY>
<!ATTLIST individual-decision %pur_att;>
<!ELEMENT contact             EMPTY>
<!ATTLIST contact             %pur_att;>
<!ELEMENT profiling           EMPTY>
<!ATTLIST profiling           %pur_att;>
<!ELEMENT historical          EMPTY>
<!ATTLIST historical          %pur_att;>
<!ELEMENT telemarketing       EMPTY>
<!ATTLIST telemarketing       %pur_att;>
<!ELEMENT other-purpose       (#PCDATA)>
<!ATTLIST other-purpose       %pur_att;>

<!-- *********** RECIPIENT ************ -->
<!ELEMENT RECIPIENT ((ours
    | same
    | other-recipient
    | delivery
    | public
    | unrelated)+,
    EXTENSION*)>
<!ELEMENT ours                  (recipient-description*)>
<!ELEMENT same                  (recipient-description*)>
<!ATTLIST same                  %pur_att;>
<!ELEMENT other-recipient       (recipient-description*)>
<!ATTLIST other-recipient       %pur_att;>
<!ELEMENT delivery              (recipient-description*)>
<!ATTLIST delivery              %pur_att;>
<!ELEMENT public                (recipient-description*)>
<!ATTLIST public                %pur_att;>
<!ELEMENT unrelated             (recipient-description*)>
<!ATTLIST unrelated             %pur_att;>
<!ELEMENT recipient-description (#PCDATA)>

<!-- *********** RETENTION ************ -->
<!ELEMENT RETENTION ((no-retention
    | stated-purpose
    | legal-requirement
    | indefinitely
    | business-practices),
    EXTENSION*)>
<!ELEMENT no-retention       EMPTY>
<!ELEMENT stated-purpose     EMPTY>
<!ELEMENT legal-requirement  EMPTY>
<!ELEMENT indefinitely       EMPTY>
<!ELEMENT business-practices EMPTY>

<!-- ************** DATA ************** -->
<!ELEMENT DATA-GROUP (DATA+, EXTENSION*)>
<!ATTLIST DATA-GROUP
    base     %URI;      "http://www.w3.org/TR/P3P/base" >
<!ELEMENT DATA (#PCDATA | CATEGORIES)*>
<!ATTLIST DATA
    ref      %URI;      #REQUIRED
    optional (yes | no) "no" >


<!-- ************** Data Schema ************* -->
<!-- *********** DATASCHEMA *********** -->
<!ELEMENT DATASCHEMA (DATA-DEF | DATA-STRUCT | EXTENSION)*>

<!ELEMENT DATA-DEF    (CATEGORIES?, LONG-DESCRIPTION?)>
<!ATTLIST DATA-DEF
    name              ID    #REQUIRED
    structref         %URI; #IMPLIED
    short-description CDATA #IMPLIED  >

<!ELEMENT DATA-STRUCT (CATEGORIES?, LONG-DESCRIPTION?)>
<!ATTLIST DATA-STRUCT
    name              ID    #REQUIRED
    structref         %URI; #IMPLIED
    short-description CDATA #IMPLIED  >

<!-- *********** CATEGORIES *********** -->
<!ELEMENT CATEGORIES (physical
  | online
  | uniqueid
  | purchase
  | financial
  | computer
  | navigation
  | interactive
  | demographic
  | content
  | state
  | political
  | health
  | preference
  | government
  | other)+>
<!ELEMENT physical    EMPTY>
<!ELEMENT online      EMPTY>
<!ELEMENT uniqueid    EMPTY>
<!ELEMENT purchase    EMPTY>
<!ELEMENT financial   EMPTY>
<!ELEMENT computer    EMPTY>
<!ELEMENT navigation  EMPTY>
<!ELEMENT interactive EMPTY>
<!ELEMENT demographic EMPTY>
<!ELEMENT content     EMPTY>
<!ELEMENT state       EMPTY>
<!ELEMENT political   EMPTY>
<!ELEMENT health      EMPTY>
<!ELEMENT preference  EMPTY>
<!ELEMENT government  EMPTY>
<!ELEMENT other       EMPTY>

<!-- *********** EXTENSION ************ -->
<!ELEMENT EXTENSION (#PCDATA)>
<!ATTLIST EXTENSION
    optional (yes | no) "yes" >

Appendix 6: ABNF Notation (Non-normative)

The formal grammar of P3P is given in this specification using a slight modification of [ABNF]. The following is a simple description of the ABNF.

name = (elements) 

where <name> is the name of the rule, <elements> is one or more rule names or terminals combined through the operands provided below. Rule names are case-insensitive. 

(element1 element2)

elements enclosed in parentheses are treated as a single element, whose contents are strictly ordered.

<a>*<b>element

at least <a> and at most <b> occurrences of the element.

(1*4<element> means one to four elements.)

<a>element

exactly <a> occurrences of the element.

(4<element> means exactly 4 elements.)

<a>*element

<a> or more elements

(4*<element> means 4 or more elements.)

*<b>element

0 to <b> elements.

(*5<element> means 0 to 5 elements.)

*element

0 or more elements.

(*<element> means 0 to infinite elements.)

[element]

optional element, equivalent to *1(element).

([element] means 0 or 1 element.)

"string" or 'string'

matches the literal string given inside double quotes.

Other notations used in the productions are:

; or /* ... */

comment.

Appendix 7: P3P Guiding Principles (Non-normative)

This appendix describes the intent of P3P development and recommends guidelines regarding the responsible use of P3P technology. An earlier version was published in the W3C Note "P3P Guiding Principles".

The Platform for Privacy Preferences Project (P3P) has been designed to be flexible and support a diverse set of user preferences, public policies, service provider polices, and applications. This flexibility will provide opportunities for using P3P in a wide variety of innovative ways that its designers had not imagined. The P3P Guiding Principles were created in order to: express the intentions of the members of the P3P working groups when designing this technology and suggest how P3P can be used most effectively in order to maximize privacy and user confidence and trust on the Web. In keeping with our goal of flexibility, this document does not place requirements upon any party. Rather, it makes recommendations about 1) what should be done to be consistent with the intentions of the P3P designers and 2) how to maximize user confidence in P3P implementations and Web services. P3P was intended to help protect privacy on the Web. We encourage the organizations, individuals, policy-makers and companies who use P3P to embrace the guiding principles in order to reach this goal.

Information Privacy

P3P has been designed to promote privacy and trust on the Web by enabling service providers to disclose their information practices, and enabling individuals to make informed decisions about the collection and use of their personal information. P3P user agents work on behalf of individuals to reach agreements with service providers about the collection and use of personal information. Trust is built upon the mutual understanding that each party will respect the agreement reached.

Service providers should preserve trust and protect privacy by applying relevant laws and principles of data protection and privacy to their information practices. The following is a list of privacy principles and guidelines that helped inform the development of P3P and may be useful to those who use P3P:

• CDMA Code of Ethics & Standards of Practice: Protection of Personal Privacy
• 1981 Council of Europe Convention For the Protection of Individuals with Regard to Automatic Processing of Personal Data
• CSA--Q830-96 Model Code for the Protection of Personal Information
• Directive 95/46/EC of the European Parliament and of the Council of 24 October 1995 on the protection of individuals with regard to the processing of personal data and on the free movement of such data
• The DMA's Marketing Online Privacy Principles and Guidance and The DMA Guidelines for Ethical Business Practice
• OECD Guidelines on the Protection of Privacy and Transborder Flows of Personal Data
• Online Privacy Alliance Guidelines for Online Privacy Policies

In addition, service providers and P3P implementers should recognize and address the special concerns surrounding children's privacy.

Notice and Communication

Service providers should provide timely and effective notices of their information practices, and user agents should provide effective tools for users to access these notices and make decisions based on them.

Service providers should:

• Communicate explicitly about data collection and use, identifying the purpose for which personal information is collected and the extent to which it may be shared.
• Use P3P privacy policies to communicate about all information they propose to collect through a Web interaction.
• Prominently post clear, human-readable privacy policies.

User agents should:

• Provide mechanisms for displaying a service's information practices to users.
• Provide users an option that allows them to easily preview and agree to or reject each transfer of personal information that the user agent facilitates.
• Not be configured by default to transfer personal information to a service provider without the user's consent.
• Inform users about the privacy-related options offered by the user agent.

Choice and Control

Users should be given the ability to make meaningful choices about the collection, use, and disclosure of personal information. Users should retain control over their personal information and decide the conditions under which they will share it.

Service providers should:

• Limit their requests to information necessary for fulfilling the level of service desired by the user. This will reduce user frustration, increase trust, and enable relationships with many users, including those who may wish to have an anonymous, pseudonymous, customized, or personalized relationship with the service.
• Obtain informed consent prior to the collection and use of personal information.
• Provide information about the ability to review and if appropriate correct personal information.

User agents should:

• Include configuration tools that allow users to customize their preferences.
• Allow users to import and customize P3P preferences from trusted parties.
• Present configuration options to users in a way that is neutral or biased towards privacy.
• Be usable without requiring the user to store user personal information as part of the installation or configuration process.

Fairness and Integrity

Service providers should treat users and their personal information with fairness and integrity. This is essential for protecting privacy and promoting trust.

Service providers should:

• Accurately represent their information practices in a clear and unambiguous manner -- never with the intention of misleading users.
• Use information only for the stated purpose and retain it only as long as necessary.
• Ensure that information is accurate, complete, and up-to-date.
• Disclose accountability and means for recourse.
• For as long as information is retained, continue to treat information according to the policy in effect when the information was collected, unless users give their informed consent to a new policy.

User agents should:

• Act only on behalf of the user according to the preferences specified by the user.
• Accurately represent the practices of the service provider.

Security

While P3P itself does not include security mechanisms, it is intended to be used in conjunction with security tools. Users' personal information should always be protected with reasonable security safeguards in keeping with the sensitivity of the information.

Service providers should:

• Provide mechanisms for protecting any personal information they collect.
• Use appropriate trusted protocols for the secure transmission of data.

User agents should:

• Provide mechanisms for protecting the personal information that users store in any data repositories maintained by the agent.
• Use appropriate trusted protocols for the secure transmission of data.
• Warn users when an insecure transport mechanism is being used.

Appendix 8: Working Group Contributors (Non-normative)

This specification was produced by the P3P Specification Working Group. The following individuals participated in the P3P Specification Working Group, chaired by Lorrie Cranor (AT&T): Mark Ackerman (University of California, Irvine), Margareta Björksten (Nokia), Eric Brunner (Engage), Joe Coco (Microsoft), Rajeev Dujari (Microsoft), Matthias Enzmann (GMD), Patrick Feng (RPI), Dan Jaye (Engage), Marit Koehntopp (Privacy Commission of Land Schleswig-Holstein, Germany), Yuichi Koike (NEC/W3C), Yusuke Koizumi (ENC), Daniel LaLiberte (Crystaliz), Marc Langheinrich (NEC/ETH Zurich), Daniel Lim (PrivacyBank), Ran Lotemberg (IDcide), Massimo Marchiori (W3C/MIT/UNIVE), Christine McKenna (Phone.com, Inc.), Mark Nottingham (Akamai), Paul Perry (Microsoft), Jules Polonetsky (Doubleckick), Martin Presler-Marshall (IBM), Joel Reidenberg (Fordham Law School), Dave Remy (Geotrust), Ari Schwartz (CDT), Noboru Shimizu (ENC), Roi Smibert (Jotter Technologies Inc.), Mark Uhrmacher (Doubleckick), Danny Weitzner (W3C), Michael Wallent (Microsoft), Rigo Wenning (W3C), Betty Whitaker (NCR), Kevin Yen (Netscape), Sam Yen (Citigroup), Alan Zausner (American Express).

The P3P Specification Working Group inherited a large part of the specification from previous P3P Working Groups. The Working Group would like to acknowledge the contributions of the members of these previous groups (affiliations shown are the members' affiliations at the time of their participation in each Working Group).

The P3P Implementation and Deployment Working Group, chaired by Rolf Nelson (W3C) and Marc Langheinrich (NEC/ETH Zurich): Mark Ackerman (University of California, Irvine), Rob Barrett (IBM), Joe Coco (Microsoft), Lorrie Cranor (AT&T), Massimo Marchiori (W3C/MIT), Gabe Montero (IBM), Stephen Morse (Netscape), Paul Perry (Microsoft), Ari Schwartz (CDT), Gabriel Speyer (Citibank), Betty Whitaker (NCR).

The P3P Syntax Working Group, chaired by Steve Lucas (Matchlogic): Lorrie Cranor (AT&T), Melissa Dunn (Microsoft), Daniel Jaye (Engage Technologies), Massimo Marchiori (W3C/MIT), Maclen Marvit (Narrowline), Max Metral (Firefly), Paul Perry (Firefly), Martin Presler-Marshall (IBM), Drummond Reed (Intermind), Joseph Reagle (W3C).

The P3P Vocabulary Harmonization Working Group, chaired by Joseph Reagle (W3C): Liz Blumenfeld (America Online), Ann Cavoukian (Information and Privacy Commission/Ontario), Scott Chalfant (Matchlogic), Lorrie Cranor (AT&T), Jim Crowe (Direct Marketing Association), Josef Dietl (W3C), David Duncan (Information and Privacy Commission/Ontario), Melissa Dunn (Microsoft), Patricica Faley (Direct Marketing Association), Marit Köhntopp (Privacy Commissioner of Schleswig-Holstein, Germany), Tony Lam (Hong Kong Privacy Commissioner's Office), Tara Lemmey (Narrowline), Jill Lesser (America Online), Steve Lucas (Matchlogic), Deirdre Mulligan (Center for Democracy and Technology), Nick Platten (Data Protection Consultant, formerly of DG XV, European Commission), Ari Schwartz (Center for Democracy and Technology), Jonathan Stark (TRUSTe).

The P3P Protocols and Data Transport Working Group, chaired by Yves Leroux (Digital): Lorrie Cranor (AT&T), Philip DesAutels (Matchlogic), Melissa Dunn (Microsoft), Peter Heymann (Intermind), Tatsuo Itabashi (Sony), Dan Jaye (Engage), Steve Lucas (Matchlogic), Jim Miller (W3C), Michael Myers (VeriSign), Paul Perry (FireFly), Martin Presler-Marshall (IBM), Joseph Reagle (W3C), Drummond Reed (Intermind), Craig Vodnik (Pencom Web Worlds).

The P3P Vocabulary Working Group, chaired by Lorrie Cranor (AT&T): Mark Ackerman (W3C), Philip DesAutels (W3C), Melissa Dunn (Microsoft), Joseph Reagle (W3C), Upendra Shardanand (Firefly).

The P3P Architecture Working Group, chaired by Martin Presler-Marshall (IBM): Mark Ackerman (W3C), Lorrie Cranor (AT&T), Philip DesAutels (W3C), Melissa Dunn (Microsoft), Joseph Reagle (W3C).

Finally, Appendix 7 is drawn from the W3C Note "P3P Guiding Principles", whose signatories are: Azer Bestavros (Bowne Internet Solutions), Ann Cavoukian (Information and Privacy Commission Ontario Canada), Lorrie Faith Cranor (AT&T Labs-Research), Josef Dietl (W3C), Daniel Jaye (Engage Technologies), Marit Köhntopp (Land Schleswig-Holstein), Tara Lemmey (Narrowline; TrustE), Steven Lucas (MatchLogic), Massimo Marchiori (W3C/MIT), Dave Marvit (Fujitsu Labs), Maclen Marvit (Narrowline Inc.), Yossi Matias (Tel Aviv University), James S. Miller (MIT), Deirdre Mulligan (Center for Democracy and Technology), Joseph Reagle (W3C), Drummond Reed (Intermind), Lawrence C. Stewart (Open Market, Inc.).

Change log from the 10 May 2000 Specification:

• A lot of typos now fixed, precisations added.
• Incorporated I18N comments (wording).
• Zero statements in a policy are now legal.
• Changed definition of <contact/>
• The "well-known location" /p3p.xml is now /w3c/p3p.xml
• Extensive modifications in all Section 2
• New opturi and name attributes for the POLICY element
• New historical purpose.
• The change_preferences attribute is now the required attribute, with different values.
• Added recipient-description tag and required attribute to better describe RECIPIENTs
• Changed definition of the <ours/> recipient
• Data types are now data structures, no primitive types specified any more
• New access log and internet access structures
• Dropped the data elements personname.formatted, postal.formatted, postal.countrycode; postal.street is now just one data element
• Guiding Principles Appendix: changes in the "Choice and Control", "Fairness and Integrity" and "Security" sections.
• The alt attribute is now mandatory in the IMG tag
• Added EXPIRY element in policies and not only in policy reference files
• Changed definition of <current/> and <admin> purposes, added new <telemarketing/> purpose, split <pseudonym/> and <profiling/> into <pseudo-analysis/>, <pseudo-decision/>, <individual-analysis>, <individual-decision>
• Changed definition of <uniqueid/> category
• Policy references in the well-known location now override eventual conflicts with HTTP-headers and/or link tag references
• Scope of policies specified by the link tag is now only on local files
• Immutability of dataschemas is now relaxed to persistence of dataschemas
• Added mandatory support of P3P user agents for the [APPEL] preference exchange language.