Is it actually possible to define a DTD, without namespaces, that allows the same element name to have two different contexts?
That depends what you mean by "context". If is certainly possible within a DTD to define an element that can be used within the content model of two (or more) other elements. It is not possible in a DTD to define an element that has a different content model (i.e., allows different child elements) depending upon its own parent.
You could accomplish something similiar to what you want by simply defining the content model to be the "union" of the content models for each "context", but this just degenerates into <!ELEMENT foo ANY>, which precludes meaningful validatoin.
If an element really has the same meaning (and therefore the same content model) where ever it is used, then reusing that element name in different contexts (where I'm taking "context" to mean parent element) is a good thing. If it doesn't have the same meaning, it deserves a different name.
How could namespaces help us here?
Forget about identifying XML elements by "name". They are identified by namespace uri/name. Hence if you declare two namespaces and use the same element name in both namespaces:
<example xmlns:ns1="http://example.com/one"; xmlns:ns2="http://example.com/two";>
<ns1:foo/>
<ns2:foo/>
</example>
then you're really talking about two different elements. It doesn't really solve this problem, it just changes the syntax by which naming collisions are avoided.
In theory you could have a different namespace for each Ant task, and hence use the same element name with an entirely different, yet strictly validatable, content model, but that doesn't really buy us anything since you'd be declaring namespaces and prefixes everywhere.
A real Ant namespace would be useful, IMHO, even if only for bookkeeping purposes. It would really help when you want to overlay another XML document with an Ant document--providing documentation, additional processing instructions, etc.
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