words (RE: extensibility in XSchema?)
W. Eliot Kimber
eliot at isogen.com
Mon Jun 22 23:35:09 BST 1998
At 07:51 PM 6/22/98, Peter Murray-Rust wrote:
>At present there are *no* defined mechanisms for either of these in XML. I
>find this amazing and regrettable (I - and others such have Rick) have been
>shouting for it). Consider:
>That's it. All we can say is there is a foo element with a bar attribute
>whose value is baz.
><!DOCTYPE foo SYSTEM "foo.dtd">
>The DOCTYPE adds the meaning, doesn't it? Nope, it says the following:
> - the root element is a foo element. But we know that already. It does NOT
>define the document as of type 'foo'.
>This is all I am asking for, but there seems to be no way to do a similar
>thing for an XML element or attribute.
You could try:
public-id="+//IDN me.com//NOTATION Foo Architecture//EN"
Which at least tells you that the document is governed by the "Foo
Architecture", which you could, given some appropriate infrastructure
(which might be a mapping from architecture public IDs to MIME types if
such a thing made sense--it's no more silly than mapping extensions to MIME
types, and at least uses names that can be made universally unique),
dereference to various definitional documents and formalisms. The pointer
to the architectural DTD lets you syntactically validate the document using
that DTD using a parser like SP and apply normal XML processing to the
Remember that, by definition, the external ID of a notation is intended to
get you to the definition of that notation, in the same way that a MIME
type gets you to the official definition of the type.
I see you as asking for two things:
1. A way to unambiguously relate a document to a governing semantic
2. A way to get the parts of that definition in some predictable ways.
Certain the PI shown above satisfies requirement 1. I'm not sure that
requirement 2 can be satisfied in a completely general way, but certainly
one could define domain-specific conventions or standards ala MIME
processing (e.g., a registry of definition documents in some agreed upon
form (which might be simply "prose")).
W. Eliot Kimber, Senior Consulting SGML Engineer
ISOGEN International Corp.
2200 N. Lamar St., Suite 230, Dallas, TX 95202. 214.953.0004
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