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(cc) creative commons

Creative Commons Metadata [DRAFT]

Status of this Document

This is a DRAFT. We welcome your initial implementations and feedback, but please be aware that details could change at any time. Please send any thoughts or comments you have to the cc-metadata mailing list (subscribe, archives) and we'll do our best to integrate them into the next draft.

Version 1.0b2, released 2002-09-02. Added prohibitions.
(previous (1.0b), latest)

1. Overview

In addition to making it easy for people to find the copyright licenses best for them, Creative Commons is working to provide simple RDF descriptions of these licenses. These descriptions will put the important points of the license in a way that makes it easy for machines to process and work from. Unlike Digital Rights Management (DRM) technology, which tries to prevent people from doing things with digital works, Creative Commons is working towards promoting these uses of works.

The license metadata can be used for a number of purposes, some basic ones are for search engines and other systems to highlight works in the Public Domain or under generous licenses. Also, users will also want to restrict their search to only things that match their required license criteria (such as only works that are available for commercial use, etc.). It could also be the basis of a system to describe the licensing of a work in plain English, to save people from having to read the increasing number of different licenses. (See Quick Reference for Choosing a Free Software License for an example of something like this in the software world.)

By standardizing a way to describe this information and providing large quantites of RDF to build on, we hope to encourage new and innovative ways to develop the commons. Of course, this metadata only provides a first approximation of the license, for information use. Users are encouraged to read the full license to make sure it meets their expectations.

2. Structure

Creative Commons Metadata describes three things: Works, Licenses and License Characteristics. Works are the things that are being licensed. We mostly use Dublin Core properties to describe them, but each one is also attached to zero-or-more licenses. The full text of the license will be available on the Web, but for the convenience of applications, a simplistic description of the license is included. This is done by linking the license to various license characteristics, the core of our metadata model.

License characteristics come in three types, permissions, prohibitions and requirements:

Permissions (rights granted by the license)

  • Reproduction (the work may be reproduced)
  • Distribution (the work (and, if authorized, derivative works) may be distributed, publicly displayed, and publicly performed)
  • Derivative Works (derivative works may be created and reproduced)

Prohibitions (things prohibited by the license)

  • Commercial use (rights may be exercised for commercial purposes)

Requirements (restrictions imposed by the license)

  • Notice (copyright and license notices must be kept intact)
  • Attribution (credit must be given to copyright holder and/or author)
  • Copyleft (derivative works, if authorized, must be licensed under the same terms as the work)

3. Format

Creative Commons uses W3C standard RDF/XML to provide and share metadata. We chose RDF for its popularity among our collaborators, its powerful extensibility mechanisms and its ease-of-integration. We envision our RDF being combined with tools from our collaborators and being distributed across the Internet. By using Internet standard URIs as our identifiers, we are immediately compatible with numerous Internet systems, and part of the emerging Semantic Web.

But it is important to note that although we produce RDF/XML, one doesn't need RDF or even XML tools to read it. Our output will be very structured so that it can be read with plain XML parsers or even simple tools like grep and sed.

But those who have access to RDF parsers can take full advantage of our model. We hope to work with the community to develop filters and tools to convert our exported RDF/XML into a variety of other formats and make it easy to use in a number of languages, environments and toolsets. If you've developed such a tool, please let us know so we can share it with the rest of the community.

Here's a sample RDF/XML export:

<rdf:RDF xmlns="http://web.resource.org/cc/"
<Work rdf:about="http://example.org/gnomophone.mp3">
  <dc:creator><w:Person><dc:title>Yo-Yo Dyne</dc:title></w:Person></dc:creator>
  <license rdf:resource="http://creativecommons.org/licenses/bcfgi" />
  <license rdf:resource="http://www.eff.org/IP/Open_licenses/eff_oal.html" />

<License rdf:about="http://creativecommons.org/licenses/bcfgp">
  <permits rdf:resource="http://web.resource.org/cc/Reproduction" />
  <permits rdf:resource="http://web.resource.org/cc/Distribution" />
  <requires rdf:resource="http://web.resource.org/cc/Notice" />
  <requires rdf:resource="http://web.resource.org/cc/Attribution" />
  <prohibits rdf:resource="http://web.resource.org/cc/CommercialUse" />

The highlighted information is the part that is likely to change from document to document, and so you application should be looking for it in particular.

Note that two license tags are included in the work description. While Creative Commons may not support multiple licenses intially, software should be prepared for data like this in case we add them in the future. When two licenses are specified, it means that the work can be used under the terms of either license (i.e. a disjunction (OR) of the two licenses).

In many places you will see "abstract URIs" with no trailing ".html" or ".rdf". Here we will be using HTTP Content Negotiation to provide various formats. Web browsers and normal users will get back an HTML page explaining things, but RDF crawlers and anyone else who provides an HTTP Accept header requesting RDF will get back a version with the RDF semantics. Of course, ".html" or ".rdf" can be added on to the end of the URL to be sure to get one or the other. For more, see the Apache manual on content negotiation.

A. RDF Schema (in RDF/XML)

<rdf:RDF xmlns="http://web.resource.org/cc/"

    <rdfs:Class rdf:about="http://web.resource.org/cc/Work">
        <rdfs:seeAlso rdf:resource="http://www.w3.org/2000/10/swap/pim/doc#Work"/>
    <rdfs:Class rdf:about="http://web.resource.org/cc/License" />
    <rdfs:Class rdf:about="http://web.resource.org/cc/Permission" />
    <rdfs:Class rdf:about="http://web.resource.org/cc/Requirement" />
    <rdfs:Class rdf:about="http://web.resource.org/cc/Prohibition" />
    <License rdf:about="http://web.resource.org/cc/PublicDomain" />
    <Permission rdf:about="http://web.resource.org/cc/Reproduction">
        <dc:description>the work may be reproduced</dc:description>
    <Permission rdf:about="http://web.resource.org/cc/Distribution">
          the work (and, if authorized, derivative works) may be distributed, 
          publicly displayed, and publicly performed
    <Permission rdf:about="http://web.resource.org/cc/DerivativeWorks">
        <dc:title>Derivative Works</dc:title>
        <dc:description>derivative works may be created and reproduced</dc:description>
    <Requirement rdf:about="http://web.resource.org/cc/Notice">
        <dc:description>copyright and license notices must be kept intact</dc:description>
    <Requirement rdf:about="http://web.resource.org/cc/Attribution">
        <dc:description>credit must be given to copyright holder and/or author</dc:description>
    <Requirement rdf:about="http://web.resource.org/cc/Copyleft">
          derivative works must be licensed under the same terms as the original work

    <Prohibition rdf:about="http://web.resource.org/cc/CommercialUse">
        <dc:title>Commercial Use</dc:title>
        <dc:description>rights may be exercised for commercial purposes</dc:description>

    <rdf:Property rdf:about="http://web.resource.org/cc/license">
        <rdfs:domain rdf:resource="http://web.resource.org/cc/Work"/>
        <rdfs:range rdf:resource="http://web.resource.org/cc/License"/>
        <rdfs:seeAlso rdf:resource="http://www.w3.org/2000/10/swap/pim/doc#ipr"/>
        <rdfs:subClassOf rdf:resource="http://purl.org/dc/elements/1.1/rights"/>
    <rdf:Property rdf:about="http://web.resource.org/cc/permits">
        <rdfs:domain rdf:resource="http://web.resource.org/cc/License"/>
        <rdfs:range rdf:resource="http://web.resource.org/cc/Permission"/>
    <rdf:Property rdf:about="http://web.resource.org/cc/requires">
        <rdfs:domain rdf:resource="http://web.resource.org/cc/License"/>
        <rdfs:range rdf:resource="http://web.resource.org/cc/Requirement"/>
    <rdf:Property rdf:about="http://web.resource.org/cc/prohibits">
        <rdfs:domain rdf:resource="http://web.resource.org/cc/License"/>
        <rdfs:range rdf:resource="http://web.resource.org/cc/Prohibition"/>

Note that the RDF schema is hosted at the independent web.resource.org project. We're hoping that these terms will be general enough to be used by all sorts of projects and licenses. As part of that, we're hosting them at an independent forum and not including any specific licenses. URIs and descriptions for Creative Commons licenses will be available later on.

Aaron Swartz, for the Creative Commons team
please send feedback to metadata@creativecommons.org