Re: [xml-dev] Mixing local and global element types

[ht@cogsci.ed.ac.uk (Henry S. Thompson)]

Ronald Bourret <rpbourret@rpbourret.com> writes:

> Is there a constraint in XML Schemas that a local element type in a
> content model can't have the same name as a global element type that is
> it's sibling? That is, you can't have a content model (A, A), where the
> first A is declared locally and the second A is declared globally?
> 
> I can't find such a beast but, then again, I can't even find a
> constraint stating that you can't declare the same global element type
> twice, so I'm probably looking in the wrong place.

If they would have the same name, then 'no', otherwise 'yes'.

That is

<g:x>
 <a/>
 <g:a/>
</g:x>

is OK if <a> is covered by a form='unqualified' local declaration and
<g:a> by a global declaration.

But if the local declaration was form='qualified', so the instance had 
to be

<g:x>
 <g:a/>
 <g:a/>
</g:x>

then not allowed (unless the declarations have the same type anyway).

Basic summary -- XML Schema _always_ treats things in terms of their
qualified names, and no content model may include two elements with
the same qualified name and different types [1]

ht

[1] http://www.w3.org/TR/xmlschema-1/#cos-element-consistent
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, part-time member of W3C Team
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	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/