Recommendations for XML Schema for Qualified Dublin Core -- PROPOSED DRAFT REVISION 2002-09-30, TGH

The original schemas can be found at: http://www.ukoln.ac.uk/metadata/dcmi/xmlschema/

Summary of Changes

• Certain DC Encoding Schemes are now limited to certain Elements and their refinements, as outlined in http://dublincore.org/documents/dcmes-qualifiers/. However, because of XML Schema limitations, it is not possible to model all of the mappings inferred by this reference. Namely, because of the overlap of encoding schemes used for Date and Coverage, the base complexType for these two elements had to combined, 'SimpleLiteralForDateAndCoverage.' This means that some of the encoding schemes that should be limited to Coverage or its refinements could be used for Date, specifically the Spatial encoding schemes. It is also possible to apply Spatial Encoding Schemes to Temporal and the opposite. Elements for which there are no defined Encoding Schemes, such as Title, are also now prohibited from having an encoding scheme. I don't think we can do much better :-(
  
  * One solution to this problem may be to differentiate encoding schemes based on the element they are used for, such as dct:Date_W3CDTF and dct:Coverage_W3CDTF, even though in reality these are the same encoding scheme. I don't really like this, but thought I would mention it.
• A minor simplification of the dcterms schema: Whenever, a substitutionGroup is used we do not have to repeat the type because this is implied by the substitutionGroup, so I have removed the type attribute from all of the elements which also have a substitutionGroup.
• Added elements, refinements, encoding schemes, and types to match the latest addtions to the DC standards, specifically: mediatior, educationLevel, dateSubmitted, dateCopyrighted, dateAccepted, conformsTo, RFC3066, and PhysicalObject.
• The dcmitype.xsd was modified to work around a bug with MSXML not correctly validating enumerations. Putting everything inside a union with just a single item solves the problem.

The Revised Schemas and their Use

Base schemas

These three schemas declare XML elements to represent the Dublin Core elements and element refinements and a number of complexTypes to represent encoding schemes:

• Schema: dc.xsd
  Target XML Namespace: http://purl.org/dc/elements/1.1/

• Schema: dcterms.xsd
  Target XML Namespace: http://purl.org/dc/terms/

• Schema: dcmitype.xsd
  Target XML Namespace: http://purl.org/dc/dcmitype/