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RE: block="substitution" in local element definitions

From: <Simon.Cox@csiro.au>
Date: Tue, 19 Feb 2002 18:16:15 +0800
Message-ID: <116D27C8E12BD411B3AB00B0D022B0B8AF09E9@yate.wa.csiro.au>
To: vdv@dyomedea.com, xmlschema-dev@w3.org
Did I miss the answer to this?  

In the primer it says [1] 

"... elements can be assigned to a special group of elements that are said
to be substitutable for a particular named element called the head element.
(Note that the *head element* must be declared as a global element.) "

I had drawn the concusion that an element must be global to be the /head/ of
a substitutionGroup, but there is no such restriction on local elements, so
they can be /members/ of substitutionGroups.  

But in Structures it says at [2] 

"[Definition:]  Through the new mechanism of element substitution groups,
XML Schemas provides a more powerful model supporting substitution of one
named element for another. Any top-level element declaration can serve as
the defining element, or head, for an element substitution group. Other
*top-level* element declarations, regardless of target namespace, can be
designated as members of the substitution group headed by this element. "

Is this the normative restriction in the spec?  
I cannot find any other reference requiring substitutionGroup members or
heads to be global/top-level ...

[1] http://www.w3.org/TR/xmlschema-0/#ref25
[2] http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/#key-equivalenceClass
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http://www.csiro.au/page.asp?type=resume&id=CoxSimon

> -----Original Message-----
> From: Eric van der Vlist [mailto:vdv@dyomedea.com]
> Sent: Wednesday, 6 February 2002 9:07 PM
> To: xmlschema-dev@w3.org
> Subject: block="substitution" in local element definitions
> 
> 
> Hi,
> 
> What's the point of allowing block="substitution" in a local element 
> definition since, unless I have missed something, local 
> elements cannot 
> be members of a substitution group ?
> 
> Thanks
> 
> Eric
> -- 
> Rendez-vous a Paris pour mes formations XML/XSLT.
>                                            
> http://dyomedea.com/formation/
> --------------------------------------------------------------
> ----------
> Eric van der Vlist       http://xmlfr.org            
> http://dyomedea.com
> http://xsltunit.org      http://4xt.org           
> http://examplotron.org
> --------------------------------------------------------------
> ----------
> 
Received on Tuesday, 19 February 2002 05:24:47 GMT

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