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   Re: [xml-dev] RE: RELAX NG and type derivation [Was:] XQuery and DTD/Sch

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From: "Dare Obasanjo" <dareo@microsoft.com>

> For those out there that may not know what W3C XML Schema was supposed to achieve 
> I suggest looking at the requirements from 1999[0] particularly the structures[1] and data types[2] sections

> [0] http://www.w3.org/TR/NOTE-xml-schema-req 
> [1] http://www.w3.org/TR/NOTE-xml-schema-req#Structural
> [2] http://www.w3.org/TR/NOTE-xml-schema-req#Datatype

It is very interesting to look back on the initial comments on the earliest drafts of XML
Schemas at 

If we look at just the first 31 days of comments, we find almost all the issues
raised that are now being addressed by ISO DSDL and RELAX NG.  

It is just as important to note that many comments did find there way into
XML Schemas--indeed, XML Schemas probably had the most careful and
thorough public comment procedure of any W3C spec, a tribute to Michael
and Dave (et al)'s thoroughness.   

Multiple Schema Languages

We find the *very first* external comment says

"First, and most importantly, the document makes no mention of the
possibility for more than one schema language, even though this is
explicitly mentioned in the charter for the WG. Given the extremely
various uses XML is likely to be put to, I think more than one schema
language will be required and so one should plan for that. (For
example, the EDI people will very likely have rather specialized
needs.) " ( from Lars Marius Garshol )

However, this is not a new request at that time: see the response
"This point has come up a number of times but I am unclear as to its intent."


Localized lexical representations (John Cowan):

Multiple lexical constraint languages -- pictures and regex (Paul Prescod)

Treatment of PCDATA as a particle

"We can make XSchema more uniform by
removing the concept of "mixed content" and by introducing a PCDATA
content token type. "  (Paul Prescod)


Unify treatment of grammars and regular expressions, modularization, co-occurrence constraints

Pluggable grammars (e.g. grammar on the document axis or grammar on an ancestor axis) 
and tokenizers and use of XPaths as particles in content models (Me)

Against Information Set contributions
"I agree with Paul.  I personally would like to drop everything that affects 
information sets from the schema language.  Hence, I oppose to information 
set contributions, archetypes, defaults, entities, notations, ...."  (Murata-san)

And an interesting comment from John Cowan:

"...XML WGs don't have any mandate for providing standards relating to

Verbal Complexity
"...the general idea of breaking down overlong sentences (134 words!) into
multiple sentences or even bulleted lists would make the Structures
document much easier to understand. " (Bob DuCharme)

Rick Jelliffe


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