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Re: PROPOSAL: Errata text to deal with the issue of predeclared 'xml' and 'xmlns' prefixes

From: Julian Reschke <julian.reschke@gmx.de>
Date: Fri, 25 Sep 2009 13:35:16 +0200
Message-ID: <4ABCAAF4.4090806@gmx.de>
To: Shane McCarron <shane@aptest.com>
CC: "public-rdf-in-xhtml-tf.w3.org" <public-rdf-in-xhtml-tf@w3.org>
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
Received on Friday, 25 September 2009 11:36:11 GMT

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