Hierarchical Namespaces (was Re: ATTN: Please comment on XHTML (before it's too late))

James Tauber jtauber at jtauber.com
Mon Sep 6 04:04:27 BST 1999

Paul wrote:
> > > Namespaces should be hierarchic. I think that now most of XML
developers  would agree.

I wrote:
> > Namespace URI's are hierarchical already, so all it would take is prefix
matching. I briefly suggested this when
> > namespaces first came out and again in more detail in a couple of posts
last week.
> > p[starts-with(namespace-uri(),"http://www.w3.org/xhtml1/")]

Paul wrote:
> Maybe we have a different understanding of what is
> hierachical  ?

Perhaps I just didn't make myself clear :-)

> http://www.w3.org/TR/xhtml1/strict
> Do I understand right that version 2 would cause
> http://www.w3.org/TR/xhtml2/strict

Well, I don't know what the XHTML folk are planning, but it doesn't really
matter. If you just what XHTML regardless of version or strictness, you
would just say


In other words, with prefix matching, you don't need to match exactly at a
directory separator "/".

> By the way -  XT is now using
> xmlns:xsl=http://www.w3.org/XSL/Transform/1.0
> This is smart. ;-)

I liked it too, but this may change in light of the current XHTML namespace

> In opposite , the article
> ( http://www.jclark.com/xml/xmlns.htm )
> ( by the same author! ;-) shows us:
> xmlns:HTML="http://www.w3.org/TR/REC-html40
> Isn't it *not* that smart?

You can still do prefix matching if they consistently use

> Would't it be better to have:
> xmlns:HTML="http://www.w3.org/HTML/4.0
> instead ?

Probably, in as much as it keeps them free from their TR URL scheme, but, as
I note above, if one is just doing prefix matching, the "/" separator isn't
necessary (although I agree with you that it is neater to have).

> PS. Actualy there are still some more problems, but thinking
> about more complex things would be easier after I'l understand
> some simple things.

As I noted in an earlier post, any (single) hierarchical representation of a
set of features forces you to prioritize axes (ie pick one permutation). If
XHTML used:


You could specify for version and underspecify for strictness, but *not* the
other way around.

James Tauber / jtauber at jtauber.com / www.jtauber.com
Maintainer of : www.xmlinfo.com,  www.xmlsoftware.com and www.schema.net
<pipe>Ceci n'est pas une pipe</pipe>

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