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Re: ERB decision, 31 October 1996

From: David G. Durand <dgd@cs.bu.edu>
Date: Fri, 1 Nov 1996 11:19:08 -0500
Message-Id: <v02130500ae9fd02c272d@[128.148.157.46]>
To: w3c-sgml-wg@w3.org
At 9:05 PM 10/31/96, Charles F. Goldfarb wrote:
>But in SGML they are always accessed and parsed, and the resulting ESIS is
>always the same. (Yes, I know that 8879 doesn't mention ESIS by name, but the
>SGML conformance testing standard certainly does.)

Yes, but we are not proposing that XML be SGML conformant, just that an
SGML-comformant processor be able to parse XML.

>Lazy parsing needn't be inconsistent with 8879 conformance, as early postings
>have demonstrated, as long as the external text entity doesn't change the state
>of the parse. (I still question whether XML can enforce this constraint.)

Well, given the work that Steve DeRose and others in SGML OPEN expended on
finding all the state-dependencies in the SGML grammar, I believe him when
he says we _already have_ guaranteed that. Or do you have a context
dependency in mind tath we have not already eliminated.

>The real problem is with entities whose text changes each time they are
>accessed, thereby yielding a different ESIS on each parse. Valid XML should
>require that external text entities be constants. Generated files should be
>accessed through attributes, where there is a chance to identify the governing
>semantics of the reference.

I'm afraid the only thing I can say is that this would be a stupid
restriction: it is not enforceable by any processor, _and_ it would make
impossible many useful applications of XML on the Web, that will
necessarily involve databases and synamic document generation. It is the
responsibility of a dynamic document implementor to produce valid XML, if
they want to validate it.

What is the point of trying to make a rule that is easy to violate, blocks
useful applications of XML, and cannot be enforced by software?

  -- David

RE delenda est.
I am not a number. I am an undefined character.
_________________________________________
David Durand              dgd@cs.bu.edu  \  david@dynamicDiagrams.com
Boston University Computer Science        \  Sr. Analyst
http://www.cs.bu.edu/students/grads/dgd/   \  Dynamic Diagrams
--------------------------------------------\  http://dynamicDiagrams.com/
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Received on Friday, 1 November 1996 11:14:08 EST

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