5.3 and Appendix A contradiction [Re: Another errata?]

james anderson James.Anderson at mecomnet.de
Tue Feb 2 21:06:09 GMT 1999

John Cowan wrote:
> Mark Birbeck wrote:
> > OK then, some have argued, at least shouldn't 'isbn' automatically be
> > part of the 'bk' namespace? Still no, I'm afraid. Every member of a
> > namespace is meant to be unique.
> Well, not quite.  An element can have the same name as a global
> attribute without problem.

In a similar vein, one unqualified attribute defined for one element can have
the same name as another unqualified attribute of another element without
sharing the same declaration.

More than one kind of "namespace" is necessary to interpret an xml document
which conforms to the spec. One kind of space maps QName's and Name's to
identifiers. Another kind maps identifiers to declarations.

The namespace spec itself does not do justice to this, and, in fact,
introduces - in relation to the notion of universal attribute names - the
impression that XML requires a Name -> Identifier -> Attribute-Declaration
mapping/namespace, when it does not. While one could accept that the illusion
of such a namespace is helpful for things like XSL patterns, this kind of
namespace is not entailed by the xml spec itself. It specifies a mapping of
the form Name -> Identifier -> Identifier -> Attribute-Declaration. That is,
it requires an element identifier in addition to an attribute identifier in
order to identify a declaration.

> ...   There is a contradiction, AFAI can see,
> between clause 5.3 and Appendix A, and obviously 5.3 is normative.

? While I recognize a contradiction between Bray's interpretation of the body
of the spec and its Appendix A, I don't seen one between the spec itself and
Appendix A.

Following A.3, example 1, line 5, the form from 5.3

<x xmlns:n1="http://www.w3.org" 
     xmlns="http://www.w3.org" >
    <good a="1"     b="2" />
    <good a="1"     n1:a="2" />

would have the equivalent (extended) Clark encoding (http://www.jclark.com/xml/xmlns.htm)

<{http://www.w3.org}x xmlns:n1="http://www.w3.org" 
                      xmlns="http://www.w3.org" >
    <{http://www.w3.org}good {{http://wwww.w3.org}good}a="1"
                             {{http://wwww.w3.org}good}b="2" />
    <{http://www.w3.org}good {{http://wwww.w3.org}good}a="1"
                             {http://www.w3.org}a="2" >

which would appear conformant. Where is the contradiction?

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