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Re: Assoc SS issue list

From: John Cowan <cowan@ccil.org>
Date: Wed, 24 Jun 2009 00:47:26 -0400
To: Simon Pieters <simonp@opera.com>
Cc: John Cowan <cowan@ccil.org>, "Grosso, Paul" <pgrosso@ptc.com>, public-xml-core-wg@w3.org
Message-ID: <20090624044725.GB13633@mercury.ccil.org>
Simon Pieters scripsit:

> Are you saying that what I described above is on the application level?

Just so.

> I think we should either have useful syntax rules, or not constrain the  
> syntax at all. Having arbitrary syntax rules are not useful for anyone,  
> IMHO.

Sure.  But consider language tags, which have three levels of validity:

1) A syntax consisting of one or more hyphen-separated subtags, each of
which consists of 1-8 alphanumeric characters (a "well-formed language
range");

2) The ANBF grammar in RFC 4646, soon to be replaced by a slightly more
restrictive grammar in RFC 4646bis (a "well-formed language tag");

3) The ABNF grammar with the further restriction that all subtags appear
in the Language Subtag Registry (a "valid language tag").

People who tag documents should of course only employ valid tags.
However, there is usually no need for processes which accept language tags
to validate them; it often suffices to check for well-formedness and then
see if the tag is one of the small subset that the particular process
has facilities to handle.  If only a fixed list of tags are meaningful
to the process, then even well-formedness checking can be dispensed with.

Likewise, there is no need in my opinion for a stylesheet-pi processor
to do more than check a pseudo-attribute value for well-formedness.
It's up to the application, which understands the context of use, to
determine which syntactically legal values are actually meaningful.
The current proposal has the processor do no syntactic validation
at all; I'm proposing something a bit more than that in the case
of the href, type, charset, and alternate pseudo-attributes.

-- 
Newbies always ask:                             John Cowan
  "Elements or attributes?                      http://www.ccil.org/~cowan
Which will serve me best?"                      cowan@ccil.org
  Those who know roar like lions;
  Wise hackers smile like tigers.                   --a tanka, or extended haiku
Received on Wednesday, 24 June 2009 04:48:16 GMT

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