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We need a EBNF spec

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Mon, 09 Jan 2006 07:46:21 +0100
To: spec-prod@w3.org
Cc: www-qa@w3.org
Message-ID: <mju3s1l4i4qv171ljpfmkg0781hebpbe60@hive.bjoern.hoehrmann.de>

Hi,

  I think W3C should publish a Recommendation or a Group Note defining
the EBNF format "defined" in http://www.w3.org/TR/REC-xml/#sec-notation
and elsewhere. This is needed because the definition in the XML 1.0
Recommendation is incomplete and W3C technical reports define more and
more variants of it for which it is not easy to tell whether they are
different or not.

For example, the XML 1.0 Recommendation does not define whether a symbol
like "Clock-value" may be used; on the right hand side this might be
interpreted as Clock - value, so maybe not, but e.g. SMIL 2.1 uses this
syntax. The result is that some EBNF parsers don't accept the grammars
in SMIL 2.1, which is bad. The lack of good parsers then leads to having
no means to verify grammars in technical reports, so the other errors in
the SMIL 2.1 grammars are even harder to find.

Some technical reports like http://www.w3.org/TR/xpath20/#id-grammar
also modify certain aspects of EBNF and/or include certain parts of the
original EBNF "specification" which makes it even harder to recognize
whether EBNF in one technical report can be processed just like EBNF in
some other specification, you have to study the details first to do
that.

Some technical reports like http://www.w3.org/TR/2005/WD-its-20051122/
and http://www.w3.org/TR/2005/WD-emma-20050916/ then use ::= grammars
without defining the format at all (and in case of EMMA it's not EBNF
as defined in XML 1.0...) and yet other technical reports refer to EBNF
http://www.w3.org/TR/2005/WD-SVGMobile12-20051207/paths.html#PathDataBNF
as defined in XML 1.0 but the grammar does not actually use it, and some
like http://www.w3.org/TR/2005/WD-P3P11-20050701/ don't even use EBNF or
another standard format, but invent new variants of other formats.

Most of this is better though than the usual handwaving reference to
some vague terms to define certain lexical constraints.

I think that a complete stand-alone reference for this format will
encourage more working groups to make use of it rather than no formal
grammar or some other format instead, encourage to make normative
reference to it rather than copy and paste some extended subsets across
multiple technical reports, encourage tool development around EBNF which
will then help to verify the technical reports, which in turn further
encourages making use of it. It will also help me to introduce {min,max}
quantifiers into EBNF.

Writing the specification should be an easy mostly copy'n'paste job.

Thanks,
-- 
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
Weinh. Str. 22 · Telefon: +49(0)621/4309674 · http://www.bjoernsworld.de
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Received on Monday, 9 January 2006 06:46:00 GMT

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