DCterms XML Schema XML Schema for http://purl.org/dc/terms/ namespace Created 2008-02-11 Created by Tim Cole (t-cole3@uiuc.edu) Tom Habing (thabing@uiuc.edu) Jane Hunter (jane@dstc.edu.au) Pete Johnston (p.johnston@ukoln.ac.uk), Carl Lagoze (lagoze@cs.cornell.edu) ______________________________________________________________________ This schema is modified from the original, April 2008, by Ray Denenberg, Library of Congress, for use by the DCX schema for SRU. The only change is that in the following two original lines: "audience" is replaced by "dc:any" Reason for the change: all other terms have substitutionGroups which are either one of the original dc terms, or "dc:any". For example, alternative has substitutionGroup title which has substitutionGroup dc:title, and so on for all variants of the original 15 terms. Then there are a number of new terms (not variants of the original 15) and they all have substitutionGroup dc:any. The only exceptions to this are mediator and educationLevel, they have a substitutionGroup which is itself a new term (audience). This causes an ambiguity when you try to validate a schema that references element from both sets. i.e ref="audience" is ambiguous with ref="mediator" (or ref="educationLevel"). ___________________________________________________________________________________ This schema declares XML elements for the DC elements and DC element refinements from the http://purl.org/dc/terms/ namespace. It reuses the complexType dc:SimpleLiteral, imported from the dc.xsd schema, which permits simple element content, and makes the xml:lang attribute available. This complexType permits the derivation of other complexTypes which would permit child elements. XML elements corresponding to DC elements are declared as substitutable for the abstract element dc:any, and XML elements corresponding to DC element refinements are defined as substitutable for the base elements which they refine. This means that the default type for all XML elements (i.e. corresponding to all DC elements and element refinements) is dc:SimpleLiteral. Encoding schemes are defined as complexTypes which are restrictions of the dc:SimpleLiteral complexType. These complexTypes restrict values to an appropriates syntax or format using data typing, regular expressions, or enumerated lists. In order to specify one of these encodings an xsi:type attribute must be used in the instance document. Also, note that one shortcoming of this approach is that any type can be applied to any of the elements or refinements. There is no convenient way to restrict types to specific elements using this approach. Changes in 2008-02-11 version: Add element declarations corresponding to 15 new dcterms URIs, and amend use of substitutionGroups. Add compexType definitions corresponding to ISO639-3, RFC4646. This group is included as a convenience for schema authors who need to refer to all the DC elements and element refinements in the http://purl.org/dc/elements/1.1/ and http://purl.org/dc/terms namespaces. N.B. Refinements available via substitution groups. This is included as a convenience for schema authors who need to define a root or container element for all of the DC elements and element refinements.