What is a namespace ... really?

[david at megginson.com]

Borden, Jonathan writes:

 > I don't see a problem with this one-to-one relationship, after all,
 > a namespace *is* defined by a uri, so... and I don't immediately
 > see why this precludes inclusion of elemements from different
 > namespaces.

What if I want to create a schema specifying that (for my set of
documents) an html:p element may contain a tei:foreign element, or a
docbook:Trademark element in addition to the regular HTML elements?

What if I want to create a schema specifying that (for my set of
documents) an html:p element may *not* contain an html:font element?

It doesn't make sense to have to create a new and different namespace
for either of these -- I'm still using the individual elements in
mostly the same way.  I could, of course, use some kind of inheritance
scheme, but I don't think the world will buy anything that requires
retrieving 5 or 10 schemas from different servers just to figure out
that an html:a element is from the HTML namespace.

 > I think the idea is that if a namespace is defined by a uri, it may
 > inherit a meaning associated with that uri, for example, suppose
 > the uri was a .DTD, would this cause a problem or work any less
 > well than a DTD which defines a default namespace and is specified
 > in a <!DOCTYPE definition?

It would cause about the same set of problems as DOCTYPE (perhaps
worse with datatyping and other niceties) -- that's why we need to get
away from it.


All the best,


David

-- 
David Megginson                 david at megginson.com
           http://www.megginson.com/

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