Another reason why namespaces URLs should not be schemas

Thu Jun 17 22:03:04 BST 1999

If I am using XHTML and I decide to refine my
document type so that headers must be inside divisions,
what do I do (if namespace URLs can be resolved to
schemas)?

Presumably, I have to derive a new schema based on
the old one, with a new URL; then I have to use that new
URL as the namespace URL. Then IE 5 and everything
that works by using the namespace URL to signify the
operation of an element will be broke.

This seems to me to be unworkable:  if I make

<html  xmlns="http://rick.com.xx/my-html.xmlschema">
...
</html>
then a rendering engine has to download my corpulent (not to
mention grumous) XML schema before it can find out that
in fact my element types are HTML.

So it seems that overloading the function of the namespace
URI to also be a schema URL would have a bad effect on
XHTML with data islands etc, or on any DTD derived from
DTDs that are built into the processor.

It seems that the situation we are reaching is that the 
namespace prefix is being treated as unique for famous
DTDs (e.g. how IE 5 treats html:) and that the
URL is being used as a schema name. If people want
to do this, that is fine, but it does not correspond to namespaces
(in fact, it corresponds more to what I suggested in 
XML-Bind  -- a simple prefixing system to make
automated renaming more manageable and a way to
bind names to schemas, except I suggested regular expression
matching not just the prefix).

Rick Jelliffe

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