Namespace Processing Hints and Rant on Scoping/Defaulting

james anderson James.Anderson at
Wed Aug 12 14:12:04 BST 1998

David Megginson wrote:
> John Cowan writes:
>  > The trouble arises in this case:
>  >
>  >      <foo:thing>This thing belongs to URI A</foo:thing>
>  >      ...
>  >      <foo:thing>This thing belongs to URI B</foo:thing>
>  >
>  > where the same prefix is meant to map to more than one URI in
>  > the course of the document.  The DTD can't supply "xmlns:foo"
>  > default attribute values for both foo:a elements, because to
>  > a DTD they are the same element type.
> This is a problem with defaulting, not with validation -- although
> DTDs can do both, the two are distinct.

They were distinct.

Both now depend on unambiguous names. With the present namespace WD,
unambiguous names depend, in turn, in some cases, on attribute defaults. Which
is circular, since that depends on an unambiguous name for the respective
element, and makes validation depend on defaulting.

I would have prefered to keep the two orthogonal, but I'm just trying to
implement it, not design it...

> Exactly the same problem occurs with architectural forms, where you
> might want to derive an element of the same type from different

It's not _quite_ the same, since those _names_ are presumed unambiguous.
> architectural forms at different points in a document.  From the
> perspective of DTD design, you have three major choices:

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