XHTML and the Three Namespaces

Marc.McDonald at Design-Intelligence.com Marc.McDonald at Design-Intelligence.com
Sat Sep 25 00:58:02 BST 1999

> At 11:46 AM 9/23/99 -0700, Andrew Layman wrote:
> >Since there have been several recent misunderstandings of my position
> >regarding namespaces and schemas, I will attempt to short-cut speculation
> >and spell-out explicitly what I believe to be the correct relation
> between
> >the two:
> >
> >1.	Namespaces serve to associate universally-unique identifiers with
> >qualified names.
> >2.	Anything so identified can have, at most, one definition.
Simon wrote:
> I think point 2 is where I get off your train.
> There is no reason why something that is uniquely identified can have only
> one definition.  Architectural forms are a classic tool for describing
> this
> situtation in markup, and in 'reality' there are many many many many many
> many cases where you can have multiple definitions, formal or otherwise,
> for the same uniquely identified thing.  (Don't get me going into
> epistemology, please...)
> html:p can have multiple definitions, one strict, one transitional, yet
> still have the same identity.  I don't see any reason why this should be
> considered a problem. While I'd like it to be identified as something
> different than letter:p, I see no reason why html:p should be constrained
> to a single definition.
> Once this deeply fictitious #2 is knocked down, I don't think the rest of
> your points stand in any 'universal' sense that must be applied to XHTML.
	I agree, in the sense it depends on what 'definition' means. Is it
syntactic as in the structural model of the element or semantic in which
case there can be hundreds of definitions. A weakness of DTDs is not being
able to have different element structure based on the context (containment)
of the element. 

	Architectures allow an element to have multiple containment
structures, so even structurally an element may have more than one

> Marc B. McDonald
> Principal Software Scientist
> Design Intelligence, Inc.
> 1111 Third Avenue, Suite 1500
> Seattle, WA  98101
> marc.mcdonald at design-intelligence.com
> Ph: 206.343-7797
> Fax: 206.343.7750
> http://www.design-intelligence.com

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