W3C home > Mailing lists > Public > w3c-sgml-wg@w3.org > October 1996

Re: C.4 Undeclared entities?

From: <lee@sq.com>
Date: Fri, 18 Oct 96 22:35:35 EDT
Message-Id: <9610190235.AA03845@sqrex.sq.com>
To: Charles@sgmlsource.com, U35395@UICVM.UIC.EDU
Cc: w3c-sgml-wg@w3.org
Charles Goldfarb argued:
> Questions like this are more easily analyzed if we avoid the confusing term
> "optional DTD".
> A missing DTD is really an implied DTD (like SGML's implied SGML
> Declaration) in which all element types have mixed content consisting of
> "(#pcdata | any element type)*" and all attributes are CDATA #REQUIRED
> (except for special conventions for ID, etc. that we might adopt).

I am not sure where this comes from -- are you saying that this is the
current state of ISO8879, or that you would like to propose this for XML?

> So there is always a DTD. Now the question is: what does a parser do with
> references to undeclared entities?
> There is no reason to do anything different
> from what is done in SGML.

This is invidious, but fallacious, reasoning.
That there is always a DTD does not mean that there is always a
user-supplied DTD.

If your implied DTD declares all the elements, it could also declare
all the entities just as easily.

> As for declaring entities automatically, I assume that means there will be a
> piece of public text containing the "automatic" declarations that is
> considered to be referenced by all DTDs (including the implied one).

It is sufficient to specify an algorithm by which such entities cn
be constructed.

For example, a language such as XML could accept an entyt of the
	base - diacritic [- diacritic ]*
and construct the appropriate sequence correctly and automatically:
might be an a with both an acute accent and a cedilla mark.
A public text containing all such possible definitions might be
very large, but this would not matter in practice, as they do not
need to be enumerated.

> Or, to put it another way, all DTDs are partial; the "automatic"
> entity declarations are the other part.

I for one would find it helpful if you could mark proposals as that,
and statements of how ISO8879 works today as such -- I recognise
that this is a weakness in my understanding of SGML, but I didn't
understand ISO8879 as specifying anything about implied DTDs.

But you cannopt possibly be talking about XML, because no consensus has
been reached about implied or partial DTDs, so one cannot say of
XML that `all DTDs are partial'.

Or are you hoping we will accept your proposal as a fact and not
question it??  that can't be right, sorry.   I'm missing something.

Received on Friday, 18 October 1996 22:35:40 UTC

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