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Re: Schema for schemas bugs?

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 23 Apr 2002 09:27:37 +0100
To: "Aung Aung" <aaung@microsoft.com>
Cc: <xmlschema-dev@w3.org>, www-xml-schema-comments@w3.org
Message-ID: <f5blmbees5i.fsf@cogsci.ed.ac.uk>
"Aung Aung" <aaung@microsoft.com> writes:

> The issues with the  xsd4xsd in MSXML are, 
> 
>  
> 
> 1. There were some confusion in the beginning about the usage of
> anySimpleType. After some clarification, we allow anySimpleType as a
> type name. However,  the spec also said "simple *ur-type definition*
> <http://www.w3.org/TR/xmlschema-1/#key-urType#key-urType>  must not be
> named as the *base type definition*
> <http://www.w3.org/TR/xmlschema-1/#st-base_type_definition#st-base_type_
> definition>  of any user-defined simple types: as it has no constraining
> facets, this would be incoherent." So, how are all the primitive data
> types have restriction facets on anySimpleType. Spes does not say how it
> allows it. Do we have to special-case all primitive dataType as
> restrict-able from anySimpleType exclusive to for parsing xsd4xsd (for
> such confusing issue, spec should implicit about how to approach it.)?

Sorry for the confusion -- you're right that the inclusion in the
sForS of the 'information only' definitions of the builtin primitive
datatypes is problematic.  I would note in our defense that the quote
above says you can't have anySimpleType as the {base type def} of and
_user-defined_ types, but I agree that taken as a user schema doc.,
the published sForS violates this constraint.

The _reason_ these defns are there is so that for _all_ builtin types
there is a well-grounded URL of the form

   http://www.w3.org/2001/XMLSchema.xsd#typename

but with hindsight we perhaps should have buried all these defns
inside <xs:documentation>.

> 3. Explicit declaration such as
> xmlns:xml=http://www.w3.org/XML/1998/namespace is now allowed by the
> namespace spec. It is explicitly stated in the xml spec that xml:lang
> (http://www.w3.org/TR/2000/REC-xml-20001006#sec-lang-tag) is a special
> attribute to allow language specification in XML, it need not xmlns:xml
> declaration.  
> 
> [2] 
> 
> PrefixedAttName
> 
> ::= 
> 
> 'xmlns:' NCName
> <http://www.w3.org/TR/1999/REC-xml-names-19990114/#NT-NCName#NT-NCName> 
> 
> [ 
> 
> NSC: Leading "XML"
> <http://www.w3.org/TR/1999/REC-xml-names-19990114/#xmlReserved#xmlReserv
> ed>  ]
> 
> Namespace Constraint: Leading "XML"
> Prefixes beginning with the three-letter sequence x, m, l, in any case
> combination, are reserved for use by XML and XML-related specifications.

Microsoft has consistently maintained that this prose allows parsers
to raise an error when confronted by the correct declaration
'xmlns:xml="http://www.w3.org/XML/1998/namespace"'.  Most of the rest
of the implementor community have read it as allowing _only_ this
declaration for that prefix, while not requiring it.  I believe there
will soon be an erratum clarifying this.

> 4. should remove the trailing space in version [version="Id:
> XMLSchema.xsd,v 1.48 2001/04/24 18:56:39 ht Exp "]. Because it is typed
> as toke, which cannot have trailing space.

It's not a token at all -- this is just a bug and will be fixed.

> 5. Some group reference that already mentioned in other threads.

Indeed.

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/
 [mail really from me _always_ has this .sig -- mail without it is forged spam]
Received on Tuesday, 23 April 2002 04:27:40 GMT

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