Re: XML, HTML, SGML, life, the universe, and everything

At 07:47 PM 11/10/96 GMT, Charles F. Goldfarb wrote:
>On Fri, 08 Nov 1996 12:17:15 -0800, Tim Bray <tbray@textuality.com> wrote:


>>Existing SGML tools can, if they're compliant, read XML today modulo
>>*only* overlapping enumerated attribute values and perhaps some 
>>mild inconsistencies as to which RE's are where.  
>The former makes XML *not* conforming SGML. The latter could avoid being
>nonconforming if the spec were written carefully (see below).

(No matter where the REs are, the *document* would still be valid SGML. 
It's the *parser behavior* which would differ slightly from "XML 
processor" behavior...)

>> XML is a subset of SGML in spirit and in fact, and
>>XML is designed so that the adjustments required in existing SGML tools
>>are trivial.
>The above statement is inconsistent on its face. If XML is a subset of 
>SGML "in
>fact", why should existing "compliant" SGML tools require any adjustments?
>can argue (but not here, please) whether a DTD-less markup language is 
>a subset
>of SGML in spirit, but to be one in fact means that conforming XML
>must conform to 8879. At present, they don't.

Regarding *writing* XML, it's certainly possible for existing tools
to need adjustment.  Most SGML-aware editors normalize things like
NET.  In order to write them out again, they'd need to be modified.
(Not that this is achingly hard to do.)


>2. XML's white space handling should be defined as a data content notation
>(XMLWS), applicable to the document element. (Suitable shortref mappings 
>prevent normal SGML RE handling from taking place.) The behavior of the
>can be dependent on attribute values and/or element types, so existing XML
>space behavior and/or other useful behaviors could be supported. (It is
>possible, incidentally, that full SGML applications might want to use this

The problem is that only one NOTATION attribute is allowed on any
one attlist, and this would be a major invasion of the user's markup
design space.  (If 8879 were to relax this, it could open up a whole
new way to do architectural forms!)