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Re: Substitution Groups

• To: "Michael Kay" <mike@s...>
• Subject: Re: Substitution Groups
• From: ht@i... (Henry S. Thompson)
• Date: Sat, 19 Feb 2005 11:08:05 +0000
• Cc: "'Paul Spencer'" <xml-dev@b...>, "'Xml-Dev'" <xml-dev@l...>
• In-reply-to: <E1D2QOT-0000Dk-00@u...> (Michael Kay's messageof "Sat, 19 Feb 2005 08:55:08 -0000")
• References: <E1D2QOT-0000Dk-00@u...>
• User-agent: Gnus/5.1006 (Gnus v5.10.6) XEmacs/21.4 (Security ThroughObscurity, linux)

"Michael Kay" <mike@s...> writes:

> The schema rec contains some contradictory statements on this.
>
> Section 3.15.3 says:
>
> "For a .QName. to resolve to a schema component of a specified kind all of
> the following must be true:
> 1 That component is a member of the value of the appropriate property of the
> schema which corresponds to the schema document within which the .QName.
> appears,"

>: in other words, component references in document A must resolve
> to something in the include tree rooted at A. 

You gloss is not accurate.  The REC also says, wrt the semantics of
<import> [1], 

 "The *schema components* (that is {type definitions}, {attribute
  declarations}, {element declarations}, {attribute group
  definitions}, {model group definitions}, {notation declarations}) of
  a schema corresponding to a <schema> element information item with
  one or more <import> element information items must include not only
  definitions or declarations corresponding to the appropriate members
  of its [children], but also, for each of those <import> element
  information items for which clause 2 above is satisfied, a set of
  *schema components* identical to all the *schema components* of I."

So the schema corresponding to a schema document is _not_ restricted
to components in that document's 'targetNamespace', and imported
components _are_ available to discharge QNames.

Action at a distance is regrettable and a source of confusion, in
specs as in object-oriented languages :-(

ht

[1] http://www.w3.org/TR/xmlschema-1/#src-import
-- 
 Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
                     Half-time member of W3C Team
    2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
            Fax: (44) 131 650-4587, e-mail: ht@i...
                   URL: http://www.ltg.ed.ac.uk/~ht/
[mail really from me _always_ has this .sig -- mail without it is forged spam]

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