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Re: PSVI: {document} property

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 05 Sep 2002 22:08:54 +0100
To: Elena Litani <elitani@ca.ibm.com>
Cc: www-xml-schema-comments@w3.org
Message-ID: <f5bheh4kuu1.fsf@cogsci.ed.ac.uk>

Elena Litani <elitani@ca.ibm.com> writes:

> Hi Henry, 
> 
> Thank you for prompt reply.
> 
> "Henry S. Thompson" wrote:
> > Um, have you looked at what the [schema documents] property requires
> > for its _value_?  
> 
> Of course :). However, I found the spec unclear. 
> 
> The definition for the [schema documents] property specifies that both
> [document location] and [document] properties exist _if_available_:
> 
> document location
> Either a URI reference, if available, otherwise ·absent· 
> document 
> A document information item, if available, otherwise ·absent·. 
> 
> 
> Your interpretation is that _if_available_ means that the lightweight
> processors do not have to expose [document] property but they still
> should expose the [document location] one (even though the spec says
> _if_available_ for this property too):

But there may not _be_ any URI, e.g. for built-in schemas.

> > So a lightweight processor can tell me where it found documents, but
> > doesn't have to build and/or expose an infoset for them.  
> 
> I am glad to hear that this is the indention. 
> 
> However, my interpretation is different: if a document was found it is
> _available_ and it is not up to a processor to choose to expose the
> property or not. And given that in some cases the spec mentions
> explicitly that lightweight processors may leave some property empty
> (and this is not the case for the [document] property), I thought that
> my interpretation is correct.

The document being found does not make a document info item
available.  XML processors are not required to implement _any_ of the
infoitems in the infoset, so a conformant processor may perfectly well 
locate a document (put its URL in the [document location] property),
parse the document, build a schema from it, but _never_ construct a
document infoitem or anything like it.  In that case, no document
information is is available.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2002, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/
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Received on Thursday, 5 September 2002 17:08:57 GMT

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