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Re: two issues: union , internal subset

From: <Noah_Mendelsohn@lotus.com>
Date: Mon, 27 Nov 2000 17:26:30 -0500
To: www-xml-schema-comments@w3.org
Message-ID: <OF91F67DD9.FA27D3A1-ON852569A4.007AF13C@lotus.com>

Morten Christensen writes:

>> Is use of internal (DTD) subset with ENTITYs etc.
>> allowed for XML Schemas?

On the one hand, the fact that the schema CR specifies both instance and
schema documents in the form of an infoset clearly indicates that entities
can be used if and only if the processor used to create your infoset
processes entities (and if that processor is XML 1.0 compliant, it will
surely resolve internal entities).

On the other hand, we might want to give a little bit of thought to section
6.3.1 of structures, which deals with the representation of schema
documents on the Web [1].  From that section:

"Schema documents on the Web must be part of documents with the MIME type
text/xml, and are represented in the standard XML schema definition form
described by layer 2 (that is as schema element information items).   NOTE:
there will often be times when a schema document will be a complete XML 1.0
document whose document element is schema. There will be other occasions in
which schema items will be contained in other documents, perhaps referenced
using fragment and/or Xpointer notation."

I _think_ but am a bit less sure that this part of the specification is
also unambiguous, as long as the note is considered along with the
normative text.  Specifically, I read this as saying:  your schema on the
Web may be a complete XML 1.0 document, which presumably means that at
least internal entities are necessarily allowed.  The note also suggests
that a schema may be an element contained within a larger document, in
which case I would think that resolution of entities is problematic.

Does this need a bit of clarification?

[1] http://www.w3.org/TR/xmlschema-1/#schema-repr

Noah Mendelsohn                                    Voice: 1-617-693-4036
Lotus Development Corp.                            Fax: 1-617-693-8676
One Rogers Street
Cambridge, MA 02142

                    "Morten M. Christensen"                                                                                       
                    <mmc@mortench.net>                  To:     www-xml-schema-comments@w3.org                                    
                    Sent by:                            cc:     (bcc: Noah Mendelsohn/CAM/Lotus)                                  
                    www-xml-schema-comments-requ        Subject:     two issues: union , internal subset                          
                    11/27/00 09:02 AM                                                                                             

I would like to register my support for the current XML Schema Candidate
Recommendation. However I have a few issues:

1) Is use of internal (DTD) subset with ENTITYs etc. allowed for XML
Schemas AND for XML document instances conforming to a schema document
?  The primer mentions internal subsets (and ENTITYs) but does not state
100% clearly if they are legal to use together with  XML

2) Example: I would like to state that an attribute must contain a
string (enumeration) + (!!) a list of IDREFS (i.e. attr="disjoint id23
id24 id27", where "disjoint" acts as a user-specific qualifier for the
set of IDs). Unfortunately, this does not appear to be possible with the
new union construction!?! I think the union construction is a MUST but
it is a bit limited right now - being able to state both
union/intersection (optionally ordered) or any combination (min,max) of
elements would be much better.

Morten Christensen (mmc@mortench.net)
AArhus, Denmark
Received on Monday, 27 November 2000 17:34:08 UTC

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