External DTD & namespaces

[David Brownell]

Andy Malakov wrote:
> 
> I want to use namespace prefixes in element declarations of the
> external/internal DTDs.
> For example, I want to define namespace "myns" and use with each DTD
> declaration:
> 
> <!ELEMENT myns:point (int, int)>
> 
> Where I should put "myns" namespace declaration?

<!ATTLIST myns:point
	xmlns:myns CDATA #FIXED
		"http://www.ptc.com/xml/something/goes/here"
	>

Keep in mind that if you put this in some external parameter
entity (e.g. the unnamed one in <!DOCTYPE foo SYSTEM "xyz.dtd">
some nonvalidating parsers will give you a hard time.  So you
may want to consider _also_ putting the declaration into your
instances:

	<myns:point xmlns:myns="http://www.ptc.com/..." ...>
		<int>42</int>
		<int>-66</int>
	</myns:point>

Where namespaces and DTDs really clash is when you might want
to change the prefix ("myns") associated with some URI.  But
namespaces actually do something that DTDs can't do -- they tie
individual elements (and attributes, though sadly not PIs) to
a specific entity, so semantics can be tied to something more
useful than an application's convention about what a TITLE is.
(Real estate vs novels, etc.)

- Dave

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