Shane McCarron wrote:
During discussions this week, Jeni and others pointed out that the
Namespaces in XML Recommendation effectively predeclares a couple of
prefixes, but that the RDFa Syntax Recommendation is silent on how these
should be handled in conforming implementations. we discussed this
briefly on the call today. I propose an errata entry to address the
issue surrounding the presence of the 'xml' and 'xmlns' mappings:
Sections 5.5 step 2 and 5.4.1 bring in the concepts associated with
Namespaces in XML as defined in [XMLNS]. One such concept is that the
prefix 'xml' is effectively predefined and has a required mapping,
although it may also be declared in a document as long as it has the
required mapping. Another is that the prefix 'xmlns' also has a
required mapping, but it cannot be declared in a document, even with
that mapping. Unfortunately, this version of the RDFa Syntax
Recommendation is silent on whether these prefix mappings are required
to be included in the collection of URI mappings at the start of
processing. Consequently, a conforming RDFa Processor MAY provide these
mappings. For maximum portability, documents that wish to reference
CURIEs via the 'xml' prefix SHOULD declare that prefix. For maximum
portability, documents SHOULD NOT reference CURIEs via the 'xmlns'
prefix (since it may not be present in some conforming RDFa Processors,
and it is illegal to declare the prefix). In a future version of this
Recommendation, it is likely that RDFa Processors will be required to
support the use of these prefixes in CURIEs without the need to declare
them in the document.
Comments?
Clarifying... this is *really* academic, right? Or are you expecting
people to actually use things which are in the "xml" or "xmlns" namespaces?
BR, Julian
