W3C home > Mailing lists > Public > www-xml-schema-comments@w3.org > October to December 2001

Re: A sixth space needed for xs:NOTATION?

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 25 Oct 2001 20:29:16 +0100
To: Eric van der Vlist <vdv@dyomedea.com>
Cc: xmlschema-dev@w3.org, www-xml-schema-comments@w3.org
Message-ID: <f5b3d471ptf.fsf@cogsci.ed.ac.uk>
Eric van der Vlist <vdv@dyomedea.com> writes:

> Arg! OTH, it doesn't
> seem completely
> compatible with it
> either since using a
> prefixed QName in an
> instance document as a
> NOTATION attribute value
> isn't allowed... and I
> thing you could add to:
> 
> 
> "For compatibility (see
> Terminology (§1.4))
> NOTATION should be used
> only on attributes."
> 
> 
> a clause saying that for
> compatibilty, qualified
> QNames should not be
> used in the lexical
> space.

Good point.

> >>Since the lexical space is "the set of all names of notations declared in the
> >>current schema" and XML Namespaces forbids colons in notation names, the
> >>lexical space is unqualified.
> >>
> > Again, DTD NOTATIONs
> > are covered by that
> > constraint, but XML
> > Schema
> 
> > NOTATIONs are not.
> >
> 
> >><picture xmlns="http://example.org/pictures" pictype="jpeg">...
> >>
> >>with pictype having a type xs:NOTATION, what's the value of pictype?
> >>
> >>Is-it {NULL, "jpeg"} or {"http://example.org/pictures", "jpeg"} ?
> >>
> > The latter.
> 
> 
> 
> I *think* I begin to understand...
> 
> <pic:picture xmlns:pic="http://example.org/pictures" pictype="jpeg">
> 
> would match {NULL,
> "jpeg"} (assuming no
> default namespaces have
> been defined in the
> ancestors of
> pic:picture).

Yes.

> and
> 
> <pic:picture xmlns:pic="http://example.org/pictures" pictype="pic:jpeg">
> 
> would be also allowed and match {"http://example.org/pictures", "jpeg"}

Yes.

> If I may suggest an editiorial revision, in
> 
> "[Definition:]NOTATION
> represents the NOTATION
> attribute type from [XML
> 1.0 (Second
> Edition)]. The ·value
> space· of NOTATION is
> the set QNames. The
> ·lexical space· of
> NOTATION is the set of
> all names of notations
> declared in the current
> schema."
> 
> 
> it would be clearer to
> say that "The ·lexical
> space· of NOTATION is
> the set of all QNames of
> notations declared in
> the current schema."

Good suggestion.

> It makes me feel very
> uneasy about the
> compatibility clause I
> mentioned above for
> prefixed QNames.
> 
> 
> Per Namespaces in XML
> and per the definition
> of QNames in W3C XML
> Schema, the two forms
> below are stricly
> equivalent and there is
> no way to constrain the
> use of one of them only:
> 
> 
> <picture xmlns="http://example.org/pictures" pictype="jpeg">
> <pic:picture xmlns:pic="http://example.org/pictures" pictype="pic:jpeg">
> 
> However, only the first
> is compatible with a DTD
> (even if the DTD is
> "namespace aware") and I
> find this to be quite
> nasty.

Agreed -- we struggled with this a lot, and this was the best
compromise we could reach.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, 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/
Received on Thursday, 25 October 2001 15:28:31 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Sunday, 6 December 2009 18:12:57 GMT