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Re: Parameter entities vs. GI name groups

From: Eve L. Maler <elm@arbortext.com>
Date: Fri, 20 Jun 1997 15:16:18 -0400
Message-Id: <>
To: Martin Bryan <mtbryan@sgml.u-net.com>
Cc: w3c-sgml-wg@w3.org
Having parameter entities for just (1) complete declarations (modules), (2)
complete model groups (nearly equivalent to GI name groups), and (3)
keywords for marked sections (switches) greatly impoverishes the set of
useful PEs.  You don't have PEs for:

4 Individual attribute specifications (common attributes)
5 Sets of elements with which you build up repeatable-OR content models
  ("classes" and "mixtures" in Jeanne's and my methodology)
6 Other content model subgroups
7 Other things that are less needful, but still useful

If I can't have at least 1 through 5, I can't get away with doing
high-quality, complex production DTDs.  If it's just too complicated to
spec and build the capability for 4 and 5, which I'm willing to believe for
V1.0, is it that useful to have 1 through 3?  I'm not sure.


At 07:03 PM 6/20/97 +0100, Martin Bryan wrote:
>At 08:09 20/6/97 -0700, Tim Bray wrote:
>>At 10:23 AM 20/06/97 -0500, David G. Durand wrote:
>>>Let's relax compatibility with SGML and make PEs into straight text macros
>>>rather than eliminating them. I think that this would be a win for users as
>>>well, since the harders thing about learning PEs is that the string
>>>substitution model is _not_ correct.
>>Exact-a-mundo.  There is nothing wrong in principle with having
>>a macro-processor facility in markup declarations, and I certainly
>>agree 100% with the people who lament the loss of PEs on these
>>grounds.  It's just that doing it in a way that's compatible with 
>>8879's replacement rules is messy and complicated and hard to 
>>Having said that, I can't at this point support simply dropping 
>>SGML compatibility on this issue (although it *would* solve the
>Come on - there are many areas of XML where you have placed semantic
>constraints on the use of valid SGML features. Why should placing
>constraints on the use of PEs be any different?
>>WG8-folk on the list; are we the only ones who would like a
>>radical simplification of the PE replacement rules, or is this
>>another pending-for-the-subset item?  How about another SGML
>>Declaration option that says PEs are just string-substituted
>>without regard for where they may be? -Tim
>We haven't got round to discussing this in committee, but the idea of adding
>an option to restrict the use of PEs to:
>a) just complete declarations
>b) just complete model groups
>c) keywords for marked sections
>would meet with my backing, and would seem to fit well with the rest of the
>subsetting we are planning to do. (Changes to the SGML declaration are
>'easy' and are expected. Changes elsewhere must be extensions.)
>Martin Bryan, 29 Oldbury Orchard, Churchdown, Glos. GL3 2PU, UK 
>Phone/Fax: +44 1452 714029  E-mail: mtbryan@sgml.u-net.com 
>For details about The SGML Centre contact http://www.sgml.u-net.com/
>For details about the Open Information Interchange initiative contact
Received on Friday, 20 June 1997 15:14:17 UTC

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