Namespaces and Parsers

John Cowan cowan at
Wed Jun 3 16:57:20 BST 1998

Peter Murray-Rust wrote:

> Thus the UN for F:foo might be [,foo]. For internal storage
> this might be held as the unique and parsable String

Alas, ":" is valid in URIs (see RFC 1738).  I suggest "^" or "~",
which are not valid in URIs.  "#" would work too, but would suggest
the wrong semantics.

>         - Xpointers. This is more serious. XPointers locate elements and
> attributes by the occurrence of QNames in the document. Thus
>         descendant(1,FOO:foo)
> will *not* find anything in our example instance. Since 'most people' agree
> that the prefix has no formal standing, perhaps XPointer V2.0 (or even the
> latest revision) could allow UniversalName substitution. I think this would
> be extremely valuable and do not see any serious downside (given that we
> are implementing namespaces anyway).

I don't think that XPointers have to be able to survive changes to
prefixes, any more than they have to be able to survive changes to
element GIs.  It is just as reasonable to change the GIs globally
as it is to change the prefixes globally, but *something* has to
stay the same in order for XPointers to work at all.

I suspect that XPointers that mention particular GIs, attribute
names, and the like should be deprecated anyway, and that what
really matters are IDs and tree-walking.

John Cowan		cowan at
	You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
	You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
		Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)

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