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Re: C.4 Undeclared entities?



At 10:32 PM 29-10-96 GMT, Henry S. Thompson wrote:
>OK, I'll bite.  David is merely the last in a moderately long list
>(i.e. at least three people :-) who have asserted without any argument
>that "users won't include a <!DOCTYPE ...>, so we shouldn't require
>one for well-formedness."  I have to say I just don't get it -- why
>ever not?  

OK, I'll bite back... I don't get why I should have to 
include, at the top of a document, a statement that 
says: There is a formal grammar definition over yonder
that can tell you what kinds of SGML elements and entities
and attributes you might find in this document. I can deduce
that all by myself -- whether I am me or a program.

I don't so much need a way to tell someone what syntax they
might encounter as I do a way to tell them what the darned
processing expectations are. That is, how do I say: "This is
a hypertext link or anchor?"

This past weekend I consolidated about twenty different style
sheets into one. I had had one stylesheet for each of twenty
document types. Then I realized that the twenty doc types had
a lot in common. I also noted that my stylesheet did not have
to limit itself to a single DTD. In fact, I could include 
GIs in my stylesheet that might not even exist in most of my DTDs.

So, now I wonder why I even need a DTD, except to tell my
application -- through its own convention -- that certain
element types are links or anchors.

>They're going to have to do a lot of other, more
>substantial, things differently from what they are used to, if they
>are hope-to-die HTML mavens, who are the only group I can suppose
>David et al. have in mind.  

I guess we can all imagine the world accepting some of the 
syntactic requirements of a useful document markup language.
Since many of us are in the biz, I guess that we expect 
to deploy tools to make it all easy for Lois.

>After all, both SGML fans and total
>newbies won't have any problem with following this rule.  Why is it
>likely that HTML fans, who after all have at least HEARD of
><!DOCTYPE ...>, will ignore this requirement

The thing is: As has been pointed out earlier, my document
may properly be a valid document according to multiple DTDs.
If I want my document to be maximally interoperable among
my document types, I won't declare that it conforms to only
one document type for perpetuity. I would rather simply have
my document and use it as I, or my application, requires.

>but not, say, the
>requirement to provide explicit end tags?  Or the requirement to quote
>all attribute values?  Seems modest by comparison, and a small price
>to pay for SGML compatibility.

I guess that I can see the value for processing tools to be
able to parse documents unambiguously. To do that, we need
a regular grammar that contains "no surprises". Explicit
end-tags and quoted strings help reduce surprises.

I don't see how a <!DOCTYPE helps an XML processor to reduce
surprises at all. The argument that a doctype declaration
can be provided by an upstream processor would seem to 
satisfy the desire for compatibility with SGML. There is 
no need to burden XML with <!DOCTYPE

Regards,

Murray


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