W3C home > Mailing lists > Public > w3c-sgml-wg@w3.org > May 1997

Re: Parameter entity references in WF docs

From: Peter Murray-Rust <Peter@ursus.demon.co.uk>
Date: Thu, 29 May 1997 08:44:54 GMT
Message-Id: <7352@ursus.demon.co.uk>
To: cbullard@hiwaay.net, Bert Bos <bert@w3.org>
Cc: w3c-sgml-wg@w3.org
In message <338CD5D2.42CC@hiwaay.net> len bullard writes:
> Bert Bos wrote:
> > 
[...]
> > >
> > > Would it be reasonable to think about saying either that
> > > (a) PErefs should not be used in the internal DTD subset, or
> > > (b) PErefs should not be used in WF docs?
> 
> My vote would be to add nothing to the spec until you get a
> 1.0 version out.  At this point that "extremely simple 

I agree with Len et. al. that we shouldn't add additional constraints to
the current V1.0 - the validation and semantics of WF docs is not yet
well explored - for myslef I can only comment on things that come up
while implementing and  Norbert and Tim have both been wrestling with PEs.  

One problem that I can see is that the borderline between a WF document 
and a validatable one may not always be clear.  What I think will become
very common is WF documents with additional ATTLISTs added in the subset.
This is almost de rigeur for XML-LINK WF docs (although in my test examples
I laboriously add XML-LINK to all tags that require them).

PEs are a reasonable tool to use for WF docs ...

<!Example[

<!DOCTYPE foo [
<!entity % embed 'SHOW="EMBED" ACTUATE="AUTO"'>
<!ATTLIST foo %embed;>
<!ATTLIST bar %embed;>
<!-- and many more -->
]>

]]>

so it is either all or nothing.  IMO PEs are well outside the mythicalCSG,
mainly because s/he has to come back recursively to comp.text.xml on a weekly
basis to keep finding out what the rules are :-) 

So it would be a nice gesture against feature bloat to excise them at this
stage.  It helps implementers (I'm not sure whether Norbert will thank
me for this suggestion since he's implemented them!) but it helps Tim.
It helps authors (I find SGML the most difficult and unnatural syntax of
any language I've met).  Recursively expanded PEs are a nightmare for new
authors and there is no effective debugger.

> dialect of SGML" rant is getting thin as the language 
> gets fat.  Sometime soon, some people will get wise and 
> will begin to question the full court press of articles 
> based on wishful thinking about this.  
> 
> > There is a better solution, and even more in the spirit of XML:
> > define XML in such a way that no parser ever needs to parse a DTD.

I don't understand this.  Certainly we shall require that a parser 
processing a WF document may have to parse the document subset - e.g.
to add ATTLISTs.  (I am assuming that WF documents can and will have
subsets that have to be processed to get the document content correct?).

	P.

-- 
Peter Murray-Rust, domestic net connection
Virtual School of Molecular Sciences
http://www.vsms.nottingham.ac.uk/
Received on Thursday, 29 May 1997 04:45:43 UTC

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