Nested DTDs

Paul Prescod paul at
Fri Jun 18 19:40:53 BST 1999

John Cowan wrote:
> Paul Prescod wrote:
> > XML ended up breaking too many other SGML rules for this to happen. The
> > empty end tag syntax was the most serious example but there are others.
> This is a myth. As says:

I'm sorry. I was speaking loosely. I meant to say that the empty end tag
syntax broke almost every tool except the one you mentioned: SP and those
that were built on top of it. Furthermore, since the most interesting and
difficult to build tools often EMIT XML, you have the problem of trying to
get them to emit the variant empty end tags (even if they were built on
SP). Even the <foo></foo> syntax doesn't help this problem because the
tools don't know to emit it.

Given that this one change broke almost everything, and given that the
whitespace, hex char ref etc. changes ended up requiring an SGML TC, XML
didn't end up being very SGML compatible in theory or practice in the end.
In 20-20 hindsight we should have fixed other things like mixed content
rules, keyword names, etc. Still, the SGML compatibility requirement gave
us some focus that is missing in e.g. the linking working group. Were it
not for that requirement we might have felt the urge to start again at
square one:

"What if we used parentheses as delimiters...and attributes could have

We might still be designing version 1.0.

 Paul Prescod  - ISOGEN Consulting Engineer speaking for only himself

[Woody Allen on Hollywood in "Annie Hall"]
Annie: "It's so clean down here."
Woody: "That's because they don't throw their garbage away. They make 
        it into television shows."

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