Conformance in XML processors

Paul Prescod papresco at
Mon Jan 19 15:44:06 GMT 1998

David Megginson wrote:
> one of the following two statements must apply:
> 1) they expect that XML documents will not typically include internal
>    cross-references; that they will not include graphics, sound,
>    video, or other non-XML material; and that they will consist of
>    only a single physical file; or
> 2) they believe that ID/IDREF, NDATA entities, notations, and external
>    text entities are overly-complicated SGML relics left in to satisfy
>    a few pedants on the WG, and that XML and XLL provide other, simpler
>    mechanisms with the same functionality.
> Clarification from the WG would be helpful here.

I don't think you can expect a coherent response from a diverse group of
people on a family of features. Also, the former statement is ridiculous
and the latter actually implies that the WG is divided on the issue.

There is a third way to read the situation: the optionality of the
features works to reassure people that XML processing is simple, but the
usefulness of them will encourage users to request them. (idea: one easy
way to encourage vendors to implement them is to depend upon them in
XLL) For instance XLL depends on ID/IDREF.

My personal feeling is:

> external text entities, 

Absolutely vital. Expansion should be expected of all processors.
XML-DEV members should apply pressure on processor vendors to handle
this, despite the laxity of the PR.

> NDATA entities, 

I suspect that the web market will be more amenable to embedded URLs.

> notations, 

MIME/HTTP can handle this.


Others seem to prefer to push this onto the application side. I don't
feel strongly enough about it to argue with them. It is clearly a
semantic restriction and there are various reasons that those are often
better handled on the application side. 

 Paul Prescod
"You have the wrong number."
"Eh? Isn't that the Odeon?"
"No, this is the Great Theater of Life. Admission is free, but the 
taxation is mortal. You come when you can, and leave when you must. The 
show is continuous. Good-night." -- Robertson Davies, "The Cunning Man"

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