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RE: SD5 - Namespaces - New Version 2

From: Andrew Layman <andrewl@microsoft.com>
Date: Fri, 23 May 1997 16:23:30 -0700
Message-ID: <7BB61B44F197D011892800805FD4F792A4BFF4@RED-03-MSG.dns.microsoft.com>
To: w3c-sgml-wg@w3.org
ARjun Ray asked a number of good questions asking for clarification of
the namespace proposal.  These are copied below, with answers preceded
by [Andrew Layman]

--Andrew Layman

> -----Original Message-----
> From:	Arjun Ray [SMTP:aray@q2.net]
> Sent:	Friday, May 23, 1997 12:39 PM
> To:	w3c-sgml-wg@w3.org
> Subject:	RE: SD5 - Namespaces - New Version 2
> On Fri, 23 May 1997, Andrew Layman wrote:
> > 	2. "Can I use an attribute from one namespace to qualify a GI
> > from another namespace?"
> > 
> > 	I see the namespace as qualifying the GI, so I don't understand
> > what it means to "use an attribute . . . to qualify a GI."  This
> must be
> > a misunderstanding on one of our parts.
> Sorry, my fault for overloading "qualify". Assuming ':' is the name
> component separator, I was basically asking about a construction like
>    ... <X:FOO Y:BAR="baz"> ...
> where within the same start-tag, an attribute is drawn from some other
> namespace than the element. Is this kosher?
	[Andrew Layman] Yes. I intend that attributes can include
namespace qualifiers. 

> > 	3. "If I can't, then does the namespace of the GI fix the
> > namespace for its attributes? Could you clarify this, please?"
> > 
> > [...]  This says nothing
> > about whether various attributes or subelements are valid, merely
> that,
> > within a tag, the namespace of the GI is to be used as the namespace
> for
> > unqualified attributes, and within an element, the namespace of the
> GI
> > is to be used as the namespace for unqualified sub-elements.
> OK, I take this to mean that in <X:FOO BAR="baz"> BAR comes from the X
> namespace. (Aside: one problem with the *term* "namespace" is the
> usual
> connotation of uniqueness within it: yet in DTDs, element names and
> attribute names are allowed to "clash". Is this a problem?) 
	[Andrew Layman] Yes, BAR comes from the X namespace.
	(Aside: The namespace proposal does not affect the issue that in
a DTD the attributes and element names are allowed to clash.)

> > 	4.	". . . what happens with colons in attribute names? Will
> > there be an extra well-formedness/validation constraint involved?" 
> > 
> > 	I do intend that attributes come from some namespace, and that
> > means that they, too, will need qualification.  So, yes, colons
> would be
> > needed in attribute names. I don't see how this affects the issue of
> > well-formedness. (Maybe I am missing some insight.)  
> Again, basically, can <X:FOO Y:BAR="baz"> be considered a well-formed
> start-tag if attributes from "foreign" namespaces are verboten One way
> to 
> look at this is to ask "Is it part of the XML parser's job to detect
> namespaces and report an appropriate parse event to the application?"
> Or
> is the detection of qualified names a job for something downstream? 
	[Andrew Layman] This is the key question here. It is not the XML
parser's job to detect namespaces. Applications that care will break out
the namespace part of the name, and look for a matching namespace
element. This could be a standard support routine shipped with parsers,
but is not--strictly speaking--a parser's job. Similarly, I do not see
validation as part of a parser's job, but as something that is (at least
logically) layered on.
Received on Friday, 23 May 1997 19:23:33 UTC

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