XML Schema Requirements

• "XML Schema Requirements." W3C Note 15 February 1999. Edited by Ashok Malhotra (IBM) and Murray Maloney (Veo Systems Inc.). The document 'specifies the purpose, basic usage scenarios, design principles, and base requirements for an XML schema language.[local archive copy]

XML Schema Formalization

[March 21, 2001]   W3C Publishes XML Schema Formalization.    A communiqué from Matthew Fuchs (Commerce One) highlights the technical significance of W3C's recent XML Schema formalization, published in a W3C Working Draft as XML Schema: Formal Description. The document supplies formal a description of XML types and validity as specified by the recently-issued Proposed Recommendation XML Schema Part 1: Structures. From the Introduction: "This formalization is a formal, declarative system for describing and naming XML Schema information, specifying XML instance type information, and validating instances against schemas. The goals of the formalization are to: (1) Provide a semantic framework for software systems that use the W3C XML Schema specification, such as the W3C XML Query Algebra; (2) Specify names for all components of an XML Schema, so that they can be uniquely identified by URIs. Such unique identifiers may be useful to XML Query, RDF, and topic maps, among others; (3) Formally define validation at a declarative level; (4) Define the mapping from the current XML Schema syntax onto the structures described here, as well as the mapping between the XML Schema component mode and our component model. Many potential applications of XML Schema may benefit from the definition of a formal model. We have focused on the material in Part I (Structures), as this is the most complex; a basic understanding of first-order predicate logic, which is part of most computer science curricula, is adequate to understand this document." [Full context]

XML Schema Definition Language - W3C Recommendation

• [May 03, 2001]   W3C XML Schema Published as a W3C Recommendation.    The World Wide Web Consortium (W3C) has announced the publication of the W3C XML Schema specification as a W3C Recommendation. A W3C 'Recommendation' "indicates that a specification is stable, contributes to Web interoperability, and has been reviewed by the W3C Membership, who are in favor of supporting its adoption by academic, industry, and research communities. XML Schemas define shared markup vocabularies, the structure of XML documents which use those vocabularies, and provide hooks to associate semantics with them. With over two years of development and testing through implementation, XML Schema provides an essential piece for XML to reach its full potential. The XML Schema specification consists of three parts. One part defines a set of simple datatypes, which can be associated with XML element types and attributes; this allows XML software to do a better job of managing dates, numbers, and other special forms of information. The second part of the specification proposes methods for describing the structure and constraining the contents of XML documents, and defines the rules governing schema-validation of documents. The third part is a primer, which explains what schemas are, how they differ from DTDs, and how someone builds a schema. XML Schema introduces new levels of flexibility that may accelerate the adoption of XML for significant industrial use. For example, a schema author can build a schema that borrows from a previous schema, but overrides it where new unique features are needed. XML Schema allows the author to determine which parts of a document may be validated, or identify parts of a document where a schema may apply. XML Schema also provides a way for users of ecommerce systems to choose which XML Schema they use to validate elements in a given namespace, thus providing better assurance in ecommerce transactions and greater security against unauthorized changes to validation rules. Further, as XML Schema are XML documents themselves, they may be managed by XML authoring tools, or through XSLT." [Full context

• In connection with the release of the Schema Recommendation, W3C has also provided for the creation of a W3C XML Schema Test Collection, announced by Henry S. Thompson (University of Edinburgh and W3C; Oriol Carbo, University of Edinburgh and W3C). "Goals and Objectives: The W3C XML Schema Test Collection work aims at coordinating test suites for W3C XML Schema processors created by different developers." The main objectives as announced 2001-05-02 are: (1) to integrate existing tests for W3C XML Schema processors in a common environment so they can be accessed publicly and shared among developers; (2) to establish a standard approach to test material IPR which meets the needs of both contributors and users; (3) to collect and develop tools to automate the execution and presentation of the test suites; (4) to offer a standard description of tests related to W3C XML Schema processors: [...]; (5) [to provide test descriptions] understandable by a developer without the need to actually view the test file(s) themselves); (6) to offer a standard presentation of test results; (7) to design additional tests and add/regularise descriptions of the existing tests; (8) in due course, to provide an XSLT-based approach to comparing XML representations of the post schema-validation infoset as produced by different processors; we will shortly announce the availability of XML Schemas for both the ordinary Infoset and the PSVInfoset. "The W3C expects to author only a small part of the collection -- we are counting on Member organisations and others to contribute the majority. To offer materials for the collection, please send e-mail to www-xml-schema-tests@w3.org." Note from Henry Thompson: "...the www-xml-schema-tests@w3.org mailing address is not a mailing list; it's for potential contributors to use to initiate discussions about contributions. For discussions of testing, I don't think we need a new mailing list; I'd expect xmlschema-dev@w3.org to be used for discussing W3C XML Schema testing..."

• Announcement: "World Wide Web Consortium Issues XML Schema as a W3C Recommendation. Two Years of Development Produces Comprehensive Solution for XML Vocabularies."
• Testimonials for XML Schema Recommendation - From Altova, Inc., Commerce One, IBM, IPR Systems, Lotus Development Corporation, Microsoft Corporation, Oracle Corporation, Reuters, Inc., SAP AG, webMethods, and University of Edinburgh.
• XML Schema Part 1: Structures. W3C Recommendation 02-May-2001. [Default] namespace: http://www.w3.org/2001/XMLSchema. Latest version URL: http://www.w3.org/TR/xmlschema-1/. Edited by Henry S. Thompson (University of Edinburgh), David Beech (Oracle Corporation), Murray Maloney (for Commerce One), and Noah Mendelsohn (Lotus Development Corporation). Available in XML format (with XML DTD and XSL stylesheet); see also the separate XML Schema and XML DTD for Part 1. [cache .ZIP, local copy]
• XML Schema Part 2: Datatypes. W3C Recommendation 02-May-2001. Latest version URL: http://www.w3.org/TR/xmlschema-2/. Edited by Paul V. Biron (Kaiser Permanente, for Health Level Seven) and Ashok Malhotra (Microsoft, formerly of IBM). Available in XML; also with a schema for built-in datatypes only. [cache]
• XML Schema Part 0: Primer. W3C Recommendation 02-May-2001. Latest version URL: http://www.w3.org/TR/xmlschema-0/. Edited by David C. Fallside (IBM). Appendices include: A. Acknowledgements; B. Simple Types & Their Facets; C. Using Entities D. Regular Expressions E. Index. [cache]
• Namespaces. [Default] namespace: http://www.w3.org/2001/XMLSchema. Also: "To facilitate usage in specifications other than the XML Schema definition language, such as those that do not want to know anything about aspects of the XML Schema definition language other than the datatypes, each 'built-in' datatype is also defined in the namespace whose URI is: http://www.w3.org/2001/XMLSchema-datatypes. This applies to both 'built-in primitive' and 'built-in derived' datatypes."
• Mail Archives for W3C XML Schema development 'xmlschema-dev@w3.org'. Send subscription requests to xmlschema-dev-request@w3.org.
• Mail Archives for 'www-xml-schema-comments'
• XML Schema type library - Sample. See the Primer (Part 0) for reference/description. [cache]
• Errata for W3C XML Schema Rec
• Translations of W3C XML Schema Rec

XML Schema Definition Language - Proposed Recommendation

[March 31, 2001] XML Schema. W3C Proposed Recommendation 30-March-2001. "This version of this Proposed Recommendation replaces that published on 16-March-2001. The only change from that draft is that the type there called 'number' is here renamed 'decimal'. This type was called 'decimal' up until the draft of 16 March 2001, so this change simply restores the original name of this type." The deadline for review of this document is Monday 16 April 2001. XML Schema Part 0: Primer; XML Schema Part 1: Structures; XML Schema Part 2: Datatypes.

[March 16, 2001]   W3C Publishes XML Schema as a Proposed Recommendation.    The W3C XML Schema specification has advanced to the 'Proposed Recommendation' stage, indicating that "the specification is stable and that implementation experience has been gathered, showing that each feature of the specification can be implemented." The three-part document has been produced as part of the W3C XML Activity. This PR version replaces the Candidate Recommendation of October 24, 2000. The deadline for review of the PR specification is Monday April 16, 2001. Review comments may be sent to the publicly archived 'xmlschema-dev' mailing list. As with the Candidate Recommendation, "The XML Schema specification consists of three parts. One part defines a set of simple datatypes, which can be associated with XML element types and attributes; this allows XML software to do a better job of managing dates, numbers, and other special forms of information. The second part of the specification proposes methods for describing the structure and constraining the contents of XML documents, and defines the rules governing schema-validation of documents. The third part is a primer, which explains what schemas are, how they differ from DTDs, and how someone builds a schema." [Full context]

See also:

• DTD changes in XML Schema from CR to PR. Provided by Robin LaFontaine, based on DeltaXML schema comparison software. See DeltaXML XML Schema [comparison] software. [source]
• [March 31, 2001] Revised Online Validator for XML Schema (XSV) and XML Schema Update Tool (XSU). Henry S. Thompson (HCRC Language Technology Group, University of Edinburgh) has announced a revised 'beta test' release of his XSV 'Validator for XML Schema' service and corresponding XSU update tool for XML Schema CR -> PR. This version of XSV supports checking XML schema documents with the namespace URI http://www.w3.org/2001/XMLSchema, corresponding to the W3C Proposed Recommendation for XML Schema. XSV is an open source "GPLed work-in-progress attempt at a conformant schema-aware processor." The online XSV interface provides two forms for W3C XML schema checking: "(1) one for checking a schema which is accessible via the Web, and/or schema-validating an instance with a schema of your own; (2) another form for use if you are behind a firewall or have a schema to check which is not accessible via the Web." In addition to source code distributions (Python), the latest version of XSV is available in a self-installing package for Win32 platforms. The XSU transformation tool provides for automated update of XML Schema documents from the XML Schema 20000922 version to the Proposed Recommendation (20010316) version. It is a service in 'beta test' which "attempts to convert valid XML schema documents with the namespace URI http://www.w3.org/2000/10/XMLSchema to valid schema documents with the namespace URI http://www.w3.org/2001/XMLSchema" using a transform sheet. In this connection, the XSU developers request sample XML schemas to provide a testing pool: they ask that users grant permission to W3C to retain input of tested XML schemas (just tick the checkbox). [Full context]

XML Schema Definition Language - Candidate Recommendation

• [October 24, 2000] Testimonials for XML Schema Candidate Recommendation. [cache]

• [October 24, 2000] Announcement (in part): A W3C press release announces the publication of XML Schema as a W3C Candidate Recommendation. "The World Wide Web Consortium (W3C) has issued XML Schema as a W3C Candidate Recommendation. Advancement of the document to Candidate Recommendation is an invitation to the Web development community at large to make implementations of XML Schema and provide technical feedback. Simply defined, XML Schemas define shared markup vocabularies and allow machines to carry out rules made by people. They provide a means for defining the structure, content and semantics of XML documents. 'Databases, ERP and EDI systems all know the difference between a date and a string of text, but before today, there was no standard way to teach your XML systems the difference. Now there is,' declared Dave Hollander, co-chair of the W3C XML Schema Working Group and CTO of Contivo, Inc. 'W3C XML Schemas bring to XML the rich data descriptions that are common to other business systems but were missing from XML. Now, developers of XML ecommerce systems can test XML Schema's ability to define XML applications that are far more sophisticated in how they describe, create, manage and validate the information that fuels B2B ecommerce.' By bringing datatypes to XML, XML Schema increases XML's power and utility to the developers of electronic commerce systems, database authors and anyone interested in using and manipulating large volumes of data on the Web. By providing better integration with XML Namespaces, it makes it easier than it has ever been to define the elements and attributes in a namespace, and to validate documents which use multiple namespaces defined by different schemas. XML Schema introduces new levels of flexibility that may accelerate the adoption of XML for significant industrial use. For example, a schema author can build a schema that borrows from a previous schema, but overrides it where new unique features are needed. his principle, called inheritance, is similar to the behavior of Cascading Style Sheets, and allows the user to develop XML Schemas that best suit their needs, without building an entirely new vocabulary from scratch. XML Schema allows the author to determine which parts of a document may be validated, or identify parts of a document where a schema may apply. XML Schema also provides a way for users of ecommerce systems to choose which XML Schema they use to validate elements in a given namespace, thus providing better assurance in ecommerce transactions and greater security against unauthorized changes to validation rules. Further, as XML Schema are XML documents themselves, they may be managed by XML authoring tools, or through XSLT. . . Candidate Recommendation is W3C's public call for implementation, an explicit invitation for W3C members and the developer community at large to review the XML Schema specification and build their own XML Schemas. This period of implementations and reporting allows the editors to learn how developers outside of the Working Group might use them, and where there may be ambiguities for implementors. Public testing and implementation contribute to a more robust XML Schema, and to more widespread use." See the full text of the announcement: "World Wide Web Consortium Issues XML Schema as a Candidate Recommendation. Implementation testing the key to Interoperability." [cache]

• [October 24, 2000] XML Schema Part 1: Structures. W3C Candidate Recommendation 24-October-2000, edited by Henry S. Thompson (University of Edinburgh), David Beech (Oracle Corp.), Murray Maloney (for Commerce One), and Noah Mendelsohn (Lotus Development Corporation). Part 1 defines the XML Schema definition language, "which offers facilities for describing the structure and constraining the contents of XML 1.0 documents, including those which exploit the XML Namespace facility. The schema language, which is itself represented in XML 1.0 and uses namespaces, substantially reconstructs and considerably extends the capabilities found in XML 1.0 document type definitions (DTDs). This specification depends on XML Schema Part 2: Datatypes. Appendix A supplies a normative "Schema for Schemas"; Appendix F contains a non-normative "DTD for Schemas"; Appendix J gives brief summaries of the substantive changes to this specification since the public working draft of 7 April 2000.

• XSD for XML Schema, [cache]

• DTD for XML Schema, [cache]

• [October 24, 2000] XML Schema Part 2: Datatypes. W3C Candidate Recommendation 24-October-2000, exited by Paul V. Biron (Kaiser Permanente, for Health Level Seven) and Ashok Malhotra (IBM). Part 2 of the specification for the XML Schema language "defines facilities for defining datatypes to be used specifications. The datatype language, which is itself represented in XML 1.0, provides a superset of the capabilities found in XML 1.0 document type definitions (DTDs) for specifying datatypes on elements and attributes." Appendix A provides the normative "Schema for Datatype Definitions" and Appendix B gives the non-normative "DTD for Datatype Definitions."

• [October 24, 2000] XML Schema Part 0: Primer. W3C Candidate Recommendation 24-October-2000, edited by David C. Fallside (IBM). "XML Schema Part 0: Primer is a non-normative document intended to provide an easily readable description of the XML Schema facilities and is oriented towards quickly understanding how to create schemas using the XML Schema language. XML Schema Part 1: Structures and XML Schema Part 2: Datatypes provide the complete normative description of the XML Schema language -- this primer describes the language features through numerous examples which are complemented by extensive references to the normative texts."

• [October 24, 2000] Commentary. See the longer memo from Henry S. Thompson (Janet Daly) with an explanation of why (I18N) WG dissented from the specification's treatment of dates and times, and the CR exit criteria. Also, in connection with this CR publication, Henry Thompson announced the availablility of a self-installing version of XSV, the W3C/University of Edinburgh XML Schema validator; 'WIN32 for now, UN*X coming soon'.

XML Schema Definition Language - Seventh Working Draft

• [September 22, 2000] XML Schema Part 1: Structures. Reference: W3C Working Draft 22-September-2000, edited by Henry S. Thompson (University of Edinburgh), David Beech (Oracle Corp.), Murray Maloney (for Commerce One), and Noah Mendelsohn (Lotus Development Corporation). The most important changes for the 07-September-2000 release are found in this Structures document. The non-normative 'Appendix H' in the Structures document supplies a "Description of changes" to the working draft since the previous public version of 07-April-2000. Some eighteen (18) changes are identified here. For example: [H1] "'Equivalence classes' have been renamed 'substitution groups', to reflect the fact that their semantics is not symmetrical; [H2] "The content model of the complexType element has been significantly changed, allowing for tighter content models and a better fit between the abstract component and its XML Representation"; [H3] "Empty content models are now signalled by an explicit empty content particle, mixed content by specifying the value true for the mixed attribute on complexType or complexContent; [H6] "A new form of schema composition operation, similar to that provided by include but allowing constrained redefinition of the included components has been added, using a redefine element"; [H8] "The defaulting for the minOccurs and maxOccurs attributes of element has been simplified: it is now 1 in both cases, with no interdependencies"; [H9] "The content model for the group element when it occurs at the top level has been tightened, to allow only a single all, choice, group, or sequence child"; [H13] "Abstract types in element declarations are now allowed." See the main news entry and editorial notes provided in Henry Thompson's announcement 'New Pre-CR Public Working Drafts of XML Schema Released'. [cache]

• [September 22, 2000] XML Schema Part 2: Datatypes. Reference: W3C Working Draft 22-September-2000, edited by Paul V. Biron (Kaiser Permanente, for Health Level Seven) and Ashok Malhotra (IBM). "XML Schema: Datatypes is part 2 of a two-part draft of the specification for the XML Schema definition language. "This document proposes facilities for defining datatypes to be used in XML Schemas as well as other XML specifications. The datatype language, which is itself represented in XML 1.0, provides a superset of the capabilities found in XML 1.0 document type definitions (DTDs) for specifying datatypes on elements and attributes." [cache]

• [September 22, 2000] XML Schema Part 0: Primer. Reference: W3C Working Draft, 22-September-2000, edited by David C. Fallside (IBM). "XML Schema Part 0: Primer is a non-normative document intended to provide an easily readable description of the XML Schema facilities and is oriented towards quickly understanding how to create schemas using the XML Schema language." [cache]

XML Schema Definition Language - Sixth Working Draft

• [April 07, 2000] XML Schema Part 0: Primer. W3C Working Draft 07-April-2000.

• [April 07, 2000] XML Schema Part 1: Structures. W3C Working Draft 07-April-2000. Last Call Ends 12 May 2000.

• [April 07, 2000] XML Schema Part 2: Datatypes. W3C Working Draft 07-April-2000. Last Call Ends 12 May 2000.

XML Schema Definition Language - Fifth Working Draft

• [February 26, 2000] XML Schema Part 0: Primer. Reference: W3C Working Draft, 25-February-2000, edited by David C. Fallside (IBM). The primer has been issued in conjunction with a new working draft [25 February 2000] of the normative tomes on XML Schema Structures and XML Schema Datatypes. Abstract: XML Schema Part 0: Primer is a non-normative document intended to provide an easily readable description of the XML Schema facilities and is oriented towards quickly understanding how to create schemas using the XML Schema language. XML Schema Part 1: Structures and XML Schema Part 2: Datatypes provide the complete normative description of the XML Schema definition language, and the primer describes the language features through numerous examples which are complemented by extensive references to the normative texts. This 'Second Torah' commentary is officially a part of the W3C XML Activity. Discrepancies between the sacred text and its commentary are noted in the Primer. Description: "This document, XML Schema Part 0: Primer, provides an easily approachable description of the XML Schema definition language, and should be used alongside the formal descriptions of the language contained in Parts 1 and 2 of the XML Schema specification. The intended audience of this document includes application developers whose programs read and write schema documents, and schema authors who need to know about the features of the language, especially features that provide functionality above and beyond what is provided by DTDs. The text assumes that you have a basic understanding of XML 1.0 and XML-Namespaces. Each major section of the primer introduces new features of the language, and describes the features in the context of concrete examples. Section 2 covers the basic mechanisms of XML Schema. It describes how to declare the elements and attributes that appear in XML documents, the distinctions between simple and complex types, defining complex types, the use of simple types for element and attribute values, schema annotation, a simple mechanism for re-using element and attribute definitions, and null values. Section 3 covers some of XML Schema's advanced features, and in particular, it describes mechanisms for deriving types from existing types, and for controlling these derivations. The section also describes mechanisms for merging together fragments of a schema from multiple sources, and for element substitution. Section 4 covers more advanced features, including a powerful mechanism for specifying uniqueness among attributes and elements, a mechanism for using types across namespaces, a mechanism for extending types based on namespaces, and a description of how documents are checked for conformance. In addition to the sections just described, the primer has a number of appendices that contain detailed reference information on simple types and an associated regular expression language. The primer is a non-normative document, which means that it does not provide a definitive (from the W3C's point of view) specification of the XML Schema language."

• [February 26, 2000] XML Schema Part 1: Structures. Reference: W3C Working Draft 25-February-2000; edited by Henry S. Thompson (University of Edinburgh), David Beech (Oracle Corp.), Murray Maloney (Commerce One), and Noah Mendelsohn (Lotus Development Corporation). The specification itself is available in XML as well as HTML format. The release includes a formal description of schema 'structures' facilities in schema and in XML DTD notation. "Following a period of review and polishing, it is the WG's intent to issue a Last Call for Review by other W3C working groups sometime during March, 2000, and to submit this specification thereafter for publication as a Candidate Recommendation." Document abstract: "XML Schema: Structures specifies the XML Schema definition language, which offers facilities for describing the structure and constraining the contents of XML 1.0 documents. The schema language, which is itself represented in XML 1.0, provides a superset of the capabilities found in XML 1.0 document type definitions (DTDs). This specification depends on XML Schema Part 2: Datatypes." Description: "The purpose of XML Schema: Structures is to define the nature of XML schemas and their component parts, provide an inventory of XML markup constructs with which to represent schemas, and define the application of schemas to XML documents. The purpose of an XML Schema: Structures schema is to define and describe a class of XML documents by using schema components to constrain and document the meaning, usage and relationships of their constituent parts: datatypes, elements and their content and attributes and their values. Schemas may also provide for the specification of additional document information, such as default values for attributes and elements. Schemas have facilities for self-documentation. Thus, XML Schema: Structures can be used to define, describe and catalogue XML vocabularies for classes of XML documents. Any application that consumes well-formed XML can use the XML Schema: Structures formalism to express syntactic, structural and value constraints applicable to its document instances. The XML Schema: Structures formalism allows a useful level of constraint checking to be described and validated for a wide spectrum of XML applications. However, the language defined by this specification does not attempt to provide all the facilities that might be needed by any application. Some applications may require constraint capabilities not expressible in this language, and so may need to perform their own additional validations."

• [February 26, 2000] XML Schema Part 2: Datatypes. Reference: W3C Working Draft 25-February-2000; edited by Paul V. Biron (Kaiser Permanente, for Health Level Seven) and Ashok Malhotra (IBM). The release includes separate documents containing the corresponding formal schema notation, an XML DTD, and schema for built-in datatypes only; there is an XML version as well. XML Schema: Datatypes is part 2 of a two-part draft of the specification for the XML Schema definition language. This document proposes facilities for defining datatypes to be used in XML Schemas and other XML specifications. The datatype language, which is itself represented in XML 1.0, provides a superset of the capabilities found in XML 1.0 document type definitions (DTDs) for specifying datatypes on elements and attributes. Rationale for Part 2: "... validity constraints exist on the content of [XML document] instances that are not expressible in XML DTDs. The limited datatyping facilities in XML have prevented validating XML processors from supplying the rigorous type checking required in these situations. The result has been that individual applications writers have had to implement type checking in an ad hoc manner. This specification addresses the need of both document authors and applications writers for a robust, extensible datatype system for XML which could be incorporated into XML processors. As discussed below, these datatypes could be used in other XML-related standards as well." The concrete requirements to be fulfilled by this specification are articulated in the XML Schema Requirements document; it states that the XML Schema Language must: (1) provide for primitive data typing, including byte, date, integer, sequence, SQL & Java primitive data types, etc.; (2) define a type system that is adequate for import/export from database systems (e.g., relational, object, OLAP); (3) distinguish requirements relating to lexical data representation vs. those governing an underlying information set; (4) allow creation of user-defined datatypes, such as datatypes that are derived from existing datatypes and which may constrain certain of its properties (e.g., range, precision, length, format). "Although the Working Group does not anticipate further substantial changes to the functionality described here, this is still a working draft, subject to change based on experience and on comment by the public and other W3C working groups. Following a period of review and polishing, it is the WG's intent to issue a Last Call for Review by other W3C working groups sometime during March, 2000, and to submit this specification thereafter for publication as a Candidate Recommendation."

XML Schema Definition Language - Fourth Working Draft

• [December 17, 1999] XML Schema Part 1: Structures (W3C Working Draft 17-December-1999). Edited by Henry S. Thompson (University of Edinburgh), David Beech (Oracle Corp.), Murray Maloney (Commerce One), and Noah Mendelsohn (Lotus Development Corporation). XML Schema: Structures represents "part 1 of a two-part draft of the specification for the XML Schema definition language. This document proposes facilities for describing the structure and constraining the contents of XML 1.0 documents. The schema language, which is itself represented in XML 1.0, provides a superset of the capabilities found in XML 1.0 document type definitions (DTDs)." The purpose of a Structures schema document is to "define and describe a class of XML documents by using these constructs to constrain and document the meaning, usage and relationships of their constituent parts: datatypes, elements and their content, attributes and their values. Schema constructs may also provide for the specification of additional information such as default values. Schemas are intended to document their own meaning, usage, and function through a common documentation vocabulary. Thus, XML Schema: Structures can be used to define, describe and catalogue XML vocabularies for classes of XML documents." [local archive copy]

• XML schema - 'Schema for Schemas'; [local archive copy]

• XML DTD - 'DTD for Schemas'; [local archive copy]

• XML Schema: Structures in XML format

• [December 20, 1999] Henry S. Thompson has made available the slides and some additional documentation from an intensive (full-day) tutorial session on the XML Schema Definition Language, presented at XML '99 in Philadelphia. The materials have been updated to match the 1999-12-17 versions of the Schema WD documents. (1) presentation slides in HTML, and (2) additional materials in HTML. Original/canonical formats: Powerpoint slides [local archive copy] and additional notes (.doc) [local archive copy]. Announced on XML-DEV 20-Dec-1999.

• dtddiff of 1999-12-17 schema proposal vis-à-vis 1999-11 WD. "Below is the result of running Earl Hood's dtddiff script to compare the DTD's from appendix B of the November and December drafts of the W3C Schema Proposal." From Bob DuCharme

• XML Schema Part 2: Datatypes (W3C Working Draft 17-December-1999) has been edited by Paul V. Biron (Kaiser Permanente, for Health Level Seven) and Ashok Malhotra (IBM). XML Schema: Datatypes presents part 2 of a two-part draft of the specification for the XML Schema definition language. This document proposes facilities for defining datatypes to be used in XML Schemas and other XML specifications. The datatype language, which is itself represented in XML 1.0, provides a superset of the capabilities found in XML 1.0 document type definitions (DTDs) for specifying datatypes on elements and attributes." It is well known that "validity constraints exist on the content of [XML document] instances that are not expressible in XML DTDs. The limited datatyping facilities in XML have prevented validating XML processors from supplying the rigorous type checking required in these situations. The result has been that individual applications writers have had to implement type checking in an ad hoc manner. This [Datatypes] specification addresses the need of both document authors and applications writers for a robust, extensible datatype system for XML which could be incorporated into XML processors." At the moment, these datatypes can be specified only "for element content that would be specified as #PCDATA and attribute values of various types in a DTD." [local archive copy]

• XML schema - Schema for datatypes; [local archive copy]

• XML DTD - DTD for datatypes; [local archive copy]

• XML Schema: Datatypes in XML Format

XML Schema Definition Language - Third Working Draft

• XML Schema Part 1: Structures. References: W3C Working Draft 5-November-1999, edited by Henry S. Thompson (University of Edinburgh), David Beech (Oracle Corp.), Murray Maloney (Commerce One), and Noah Mendelsohn (Lotus Development Corporation).

• Structures - HTML Format

• Structures - XML format

• Structures - XML Schema

• Structures - XML DTD

• Comments to www-xml-schema-comments@w3.org; and the mail archive

• dtddiff of XSDL November and September drafts, supplied by Bob DuCharme.

• XML Schema Part 2: Datatypes. References: W3C Working Draft 05-November-1999, edited by Paul V. Biron (Kaiser Permanente, for Health Level Seven) and Ashok Malhotra (IBM).

• Datatypes - XML format

• Datatypes - XML Schema

• Datatypes - XML DTD

XML Schema Definition Language - Second Working Draft

• XML Schema Part 1: Structures. Reference: W3C Working Draft 24-September-1999, edited by Henry S. Thompson (University of Edinburgh), David Beech (Oracle), Murray Maloney (Commerce One), and Noah Mendelsohn (Lotus). Part 1 "proposes facilities for describing the structure and constraining the contents of XML 1.0 documents. The schema language, which is itself represented in XML 1.0, provides a superset of the capabilities found in XML 1.0 document type definitions (DTDs). . . The purpose of the Structures specification is to provide an inventory of XML markup constructs with which to write schemas." Such a schema is used "to define and describe a class of XML documents by using these constructs to constrain and document the meaning, usage and relationships of their constituent parts: datatypes, elements and their content, attributes and their values, entities and their contents and notations. Schema constructs may also provide for the specification of additional information such as default values. Schemas are intended to document their own meaning, usage, and function through a common documentation vocabulary. Thus, the Structures specification can be used to define, describe and catalogue XML vocabularies for classes of XML documents. Any application that consumes well-formed XML can use the XML Schema: Structures formalism to express syntactic, structural and value constraints applicable to its document instances. The Structures formalism will allow a useful level of constraint checking to be described and validated for a wide spectrum of XML applications. However, the language defined by this specification does not attempt to provide all the facilities that might be needed by any application. Some applications may require constraint capabilities not expressible in this language, and so may need to perform their own additional validations."

  • Structures - HTML Version, [local archive copy]
  • XML format, [local archive copy]
  • XML schema, [local archive copy]
  • XML DTD, [local archive copy]
  • Comments to:www-xml-schema-comments@w3.org
  • Comments public archive.
  • XML Schema Part 1: Structures - Proposed Updates from Simplification Task Force. 13-August-1999. Based on W3C Working Draft 19-July-1999. Taskforce members: D. Beech, P. Biron, A. Brown, P. Chen, D. Fallside (ed), M. Fuchs, M. Murata, J. Robie. "The updates proposed in this document take the form of new text to replace text currently existing in sections 2, 3 and Appendix B of the 19 July XML Schema: Structures working draft. Within sections 2 and 3 of this proposal, subsections indicated by only headings are assumed to contain the text of the July 19 draft, although note that the heading itself of section 2.4 is updated." [local archive copy]
  • Proposal by the "Simple Syntax" Taskforce. August 13, 1999. Taskforce members: D. Beech, P. Biron, A. Brown, P. Chen, D. Fallside (ed), M. Fuchs, M. Murata, J. Robie. "This paper describes the recommendation of the "Simple Syntax" Taskforce for simplifying the syntax of element definitions, type definitions, and element usage within content models. It provides a syntax description, examples, in addition to a summary of alternatives explored. A companion document XML Schema Part 1: Structures - Proposed Updates from Simplification Taskforce proposes new text for the Structures working draft." [local archive copy]
  • Note on the 2nd WD, by Henry S. Thompson
  • dtddiff of XSDL 5/99 and 9/99 - Provided by Bob DuCharme, XML-DEV.

• XML Schema Part 2: Datatypes. Reference: W3C Working Draft 24-September-1999, edited by Paul V. Biron (Kaiser Permanente, for Health Level Seven) and Ashok Malhotra (IBM). The Datatypes document "specifies a language for defining datatypes to be used in XML Schemas and possibly elsewhere." As explained in the W3C's XML Schema Requirements document, the Datatypes design is motivated by the recognition that "document authors, including authors of traditional documents and those transporting data in XML, often require a high degree of type checking to ensure robustness in document understanding and data interchange." In many cases, "validity constraints exist on the content of the [XML] instances that are not expressible in XML DTDs. The limited datatyping facilities in XML have prevented validating XML processors from supplying the rigorous type checking required in these situations. The result has been that individual applications writers have had to implement type checking in an ad hoc manner. This [Datatypes] specification addresses the need of both document authors and applications writers for a robust, extensible datatype system for XML which could be incorporated into XML processors." The facilities in the Datatypes WD have been designed in light of the formal requirements, which stipulate that the XML Schema Language must: (1) provide for primitive data typing, including byte, date, integer, sequence, SQL & Java primitive data types, etc.; (2) define a type system that is adequate for import/export from database systems (e.g., relational, object, OLAP); (3) distinguish requirements relating to lexical data representation vs. those governing an underlying information set; and (4) allow creation of user-defined datatypes, such as datatypes that are derived from existing datatypes and which may constrain certain of its properties (e.g., range, precision, length, format)."

  • Datatypes - HTML Version, [local archive copy]
  • XML format, [local archive copy]
  • XML schema, [local archive copy]
  • XML DTD, [local archive copy]
  • Comments to:www-xml-schema-comments@w3.org
  • Comments public archive.

XML Schema Definition Language - First Working Draft

• XML Schema Part 1: Structures. W3C Working Draft 6-May-1999. Edited by David Beech (Oracle), Scott Lawrence (Agranat Systems), Murray Maloney (Commerce One), Noah Mendelsohn (Lotus), and Henry S. Thompson (University of Edinburgh). Part 1 'proposes facilities for associating datatypes with XML element types and attributes; this will allow XML software to do a better job of managing dates, numbers, and other special forms of information.'

  • HTML Version, [local archive copy]
  • XML Version; [local archive copy]
  • Accompanying schema, [local archive copy]
  • Accompanying DTD, [local archive copy]
  • Press Release: "World Wide Web Consortium Releases First Working Drafts of XML Schema Specification. W3C Members Collaborate to Improve and Standardize Needed Technology." [local archive copy]
  • Send comments to: www-xml-schema-comments@w3.org
  • Comments archived

• XML Schema Part 2: Datatypes. World Wide Web Consortium Working Draft 06-May-1999. Edited by Paul V. Biron (Kaiser Permanente, for Health Level Seven) and Ashok Malhotra (IBM). Part 2 of the specification 'proposes methods for describing the structure and constraining the contents of XML documents.'

  • HTML Version; [local archive copy]
  • Accompanying schema, [local archive copy]
  • Accompanying DTD, [local archive copy]
  • Send comments to: www-xml-schema-comments@w3.org
  • Comments archived