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Re: We need a EBNF spec

From: Felix Sasaki <fsasaki@w3.org>
Date: Mon, 09 Jan 2006 16:56:00 +0900
To: "Ian Hickson" <ian@hixie.ch>, "Bjoern Hoehrmann" <derhoermi@gmx.net>
Cc: spec-prod@w3.org, www-qa@w3.org
Message-ID: <op.s23pnma3x1753t@ibm-60d333fc0ec>

+1 for the proposal of Bjoern to standardize the EBNF, and my many thanks  
as a co-author of http://www.w3.org/TR/2005/WD-its-20051122/ for pointing  
out that we need to define the EBNF format in that document. If you want  
to make that point as a comment on the working draft, please tell me or  
just send a mail to www-i18n-comments@w3.org

Also an encouragement to use the EBNF. At least for specification whose  
semantics is very closely bounded to a context free grammar with a lot of  
non-terminals (like XPath, XQuery, XML itself, ...), the EBNF helps the  
reader and implementer a lot. Relying mainly on formal grammar was a main  
design principle of XML, see  
http://www.textuality.com/sgml-erb/dd-1996-0001.html (principle 8).

Regards, Felix

On Mon, 09 Jan 2006 16:05:01 +0900, Ian Hickson <ian@hixie.ch> wrote:

> On Mon, 9 Jan 2006, Bjoern Hoehrmann wrote:
>> 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.
> An alternative would be for the W3C to standardise on ISO 14977:1996 or
> RFC 2234.
> Personally I would discourage the use of BNF, however, as it makes it  
> very
> difficult to define error handling rules, and specifications often forget
> to define how to go from the parsed tree to the semantics that the
> specification defines, leaving it up to UA implementors to work out the
> implied mapping.
> For example, as far as I can tell, there is nothing in the XML 1.0 spec
> that says what the syntax of an XML Declaration (as found in a prolog)  
> is.

http://www.w3.org/TR/REC-xml/#NT-XMLDecl does not fulfill your needs?

Regards, Felix.

> One can make a guess, but the spec doesn't say whether we are right. The
> reliance on EBNF has made it easier to leave the mapping of the strict
> syntax definitions to the actual semantics to implication than to make  
> the
> spec full and complete.
Received on Monday, 9 January 2006 07:56:14 UTC

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