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RE: Namespaces 'n Schemas

• To: "Richard Tobin" <richard@c...>, <xml-dev@l...>
• Subject: RE: Namespaces 'n Schemas
• From: "Jim Theriot" <Jim.Theriot@p...>
• Date: Tue, 26 Mar 2002 13:31:37 -0600
• Importance: Normal
• In-reply-to: <200203261803.SAA10399@m...>

Richard,

Possibly I didn't state my issues very well ...

> In article <NDBBKGBEKKCNMDLMKFOIMEHMDNAA.Jim.Theriot@P...> you write:
>
> >According to the Namespaces spec, each element in an XML
> document (qualified
> >or unqualified) has a type name comprised of a local name and an optional
> >namespace name.
>
> The term "element type" as used in the Namespaces spec is inherited
> from SGML.  In SGML's DTDs (and XML's, of course) there are no local
> declarations, so "element types" match one-to-one with ELEMENT
> declarations.

The term 'element type' is used the current XML spec and the Namespaces
spec;  not defined in either, but apparently used consistently, despite its
derivation from legacy sources.

> XML Schemas do indeed change this.  Even in an instance that doesn't
> use namespaces, the same "element type" may be validated by different
> element declarations in different places.

Yes, I understand that.  By the way, your use of "element type" in the above
statement (as the type name of a type which is not necessarily global), is
consistent with the use of the term in the Namespaces spec.

> >Would the namespace
> >associations resolved by the Namespaces algorithm ever be
> different than the
> >association resolved according to the XML Schema spec?
>
> No, because XML Schema doesn't go so far as to put the unqualified
> local elements in namespace of their parent.  It doesn't, in
> particular, change their [namespace name] property in the infoset.  It
> just chooses a declaration to validate them against based on the
> namespace of their parent.

It seems that the question of validity can be separated into two parts:
  1) given an element in an instance, what is its namespace name,
     i. e. what does the parser put as [namespace name] in the infoset, and
  2) given the namespace name and local name and parentage of an element,
     is it valid, i. e. what does the validator do with
     what it finds in [namespace name] the infoset.

Since the validator acts on the infoset, it seems that question 1) will
necessarily have been answered for it in advance by the parser.  And since
the Infoset spec refers to the Namespaces spec but not to the XML Schema
spec, I assume that the process of generating an infoset answers question 1)
for each element in the instance according to the namespaces spec,
independently of the XML Schema spec, and independently of any information
in any applicable schema instance. (I assume that the XML Schema spec
doesn't also specify a valid parse process, one in which a schema instance
is required input ...)

My conclusion (which I sincerely hope someone will show is incorrect) is
that, with respect to Namespaces, the processing which XML Schema defines on
an infoset is inconsistent with the current Infoset and Namespaces specs.

Regards,
Jim

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