What is a namespace ... really?

James Tauber jtauber at jtauber.com
Fri Jan 15 18:46:32 GMT 1999

>(1) A namespace is just a URI.  It references some domain.  It is simply
>there to tell an application/processor what domain the associated XML
>elements hail from.

Well, it doesn't even need to be the domain the elements hail from, just a
URI that no one else would use for different elements. Universal uniqueness
(is that a tautology) is what namespaces are all about.

If I developed my own elements, I might use the URI http://www.jtauber.com/
If I want to use your elements but there is nothing obvious to use for a
namespace, I might use http://www.jtauber.com/costello/
I can be fairly sure that it's unique (who else would use my domain). There
doesn't even have to be a resource at that URI.

>(2) A namespace is a URI to a DTD.

No. It doesn't have to be at all (although it *could* be and a URI for a DTD
is as good a URI as any and better than most)


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