Eve Maler has announced the public availability of a W3C note describing a possible solution for mapping linking information from other XML vocabularies into XLink attributes.

This note had been mentioned as work in progress when Philipp Hoschka revealed that generic link recognition of XHTML and SMIL Links was necessary before XML Schema and XLink could exit a Candidate Recommendation status.

It describes a three-step process:

1. Schema-XLink, a XML Schema, would be published for the XLink vocabulary.
2. XML Schemas would be written for XML vocabularies wishing to map their linking information to XLink. These schemas would use the Schema-XLink data types and define fixed attributes where needed.
3. Tools would be developed that would map the attributes based on type derivation available in these schemas.

The note doesn't say if elements could also be mapped to XLink attributes.

It is described as a "possible XML Schema-based solution to the need to use XLink in XML-based languages such as XHTML 1.0." The final solution to this issue appears to be out of the scope of the current XML Linking Working Group:

This Note cannot dictate what problems future XML Linking Working Groups will be chartered to solve, nor what solutions they will use to solve them.

The document also mentions that XML Schema is lacking features needed to fully validate the XLink vocabulary:

XML Schema does not have facilities to specify additional normative constraints of the style that XLink needs

After RDF, whose syntax is too flexible (and does allow unordered element groups), and XSLT which would need to specify the relative position of text nodes and elements within mixed modes nodes and a XPath data type (two features recently rejected by the XML Schema Working Group), XLink appears to be the third W3C XML vocabulary for which XML Schema is not a good fit.

Other stories:

• XML Schema prompted to glue together XLink to XHTML, SVG and SMIL
• Simple schemas make for complex documents