ISO JTC1/SC34/WG1 recently approved a proposal for a new work item on a 'Document Schema Definition Language (DSDL)'. The NP was submitted by the British Standards Institution (BSI), who have been asked to appoint an editor "to complete a first draft based on extensions to RELAX-NG and forward it to SC34 for review." The specification would govern "the definition of document structures, data types and data relationship constraints that can be applied to data represented using the ISO/IEC 8879 Standard Generalized Markup Language and its derivatives, such as ISO/IEC 10744, Hypermedia/Time-based Structuring Language (HyTime), and the W3C Extensible Markup Language (XML)." Background for the NP: "SGML Document Type Definitions (DTDs) allow document structures to be formally modelled but do not allow details of data types or data relationships to be recorded in an XML-compatible way. While the W3C XML Schema Definition language (XSD) does allow data types to be used to validate the contents of SGML elements and values of attributes, it does not allow the relationships between the values of different attributes and contents of elements to be validated. A new, compact, efficient and XML document type definition for the integrated description of document structures, data types and data relationships will make it possible to automate the processing of structured information resources to the level required by business users, which has a higher level of requirements than those identified from the publishing community for which SGML was originally developed. The standard will also define the scope and notation for converting and interworking a core subset of document structure, data type, and data relationship constraint models among the three notations: DSDL, DTD declarations, and XSDL." According to the draft proposal, a "preparatory draft will be contributed by the UK National Body for the SC34 meeting in December 2001. Liaison with the W3C XML Coordinating Committee will be undertaken to keep the standard aligned with the work being done to manage information sets developed for XML. The committee expects to be able to integrate the best practices of [recent] proposals to form the basis of a first draft of the new standard... [for example,] the RELAX TR developed by the Japanese National Body as ISO 22250 and the TREX language developed by James Clark (the editor of the ISO/IEC 10179 Document Style Semantics and Specification Language) both propose efficient XML representations of document models, including data types. The widely acknowledged XML Schema Data Types specification will be referenced. The Schematron language allows the relationships between data elements and attributes to be described."

Bibliographic reference: Proposal for a New Work Item. Title: "Document Schema Definition Language (DSDL)." Date of presentation of proposal: 2001-05-23. Proposer: Martin Bryan, ISO/IEC JTC 1/SC 34. Secretariat: National Body (Acronym) BSI. NWI is expected to lead to a single International Standard. NWI proposed for assignment to ISO/IEC JTC 1 / SC34 / WG1. [Martin Bryan will contribute a first draft for the requirements statement; James Clark may be proposed as editor by BSI.]