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Re: Case sensitivity bug, CSS

From: Mukul Sabharwal <mukul@pauridge.dyndns.org>
Date: Sat, 19 Jul 2003 05:44:50 -0500
To: "'Jukka K. Korpela'" <jkorpela@cs.tut.fi>, <www-validator@w3.org>
Message-ID: <000c01c34de2$c8038f50$e0807518@PAURIDGE>

Ahhh... Well I'm new to CSS. But because I started off with the STRICT
HTML DTD, and well I never saw any need for validation until now, when
I'm venturing to make my own simple browser. And now that I've checked
that CSS identifiers (class and ID) are case sensitive.

Which doesn't apply to in somehow the HTML 4.01 Transitional. Internet
Explorer for one does not put the bar of case sensitiveness if your DTD
is Transitional, only does it, If it is strict.


Oh yeah, that was a typo.

Thanks, this clears up some stuff.


-----Original Message-----
From: Jukka K. Korpela [mailto:jkorpela@cs.tut.fi] 
Sent: Tuesday, July 15, 2003 11:28 PM
To: www-validator@w3.org
Cc: mukul@pauridge.dyndns.org
Subject: Re: Case sensitivty bug, CSS


On Fri, 11 Jul 2003, Mukul Sabharwal wrote:

> I just wanted to let you guys know, that the HTML validator, on the
> strict html dtd, does not point out that if you are using :
>
> <META HTTP-EQUIV="Content-Type" CONTENT="TEXT/HTML; charset:UTF-8">

The question was answered by Bjoern Hoehrmann, who briefly pointed at a
recorded bug in the "CSS Validator". But I think that a short additional
note is in order (on the www-validator list only), for clarification.

Media type names are case insensitive, so TEXT/HTML is just as good as
text/html. Media type name structure is defined in MIME specifications,
and the statement that they are case insensitive seems to have been
buried deep into RFC 2045:
http://www.mhonarc.org/~ehood/MIME/2045/rfc2045.html#5.1

But this is _not_ checked in any way by a validator. The situation is
confused, first, by calling various checkers like "CSS Validator"
validators and, second, by the fact that some validators and other
checkers may _process_ element attributes. In the validation process, a
validator (in the SGML sense of the word) never "does" anything with
attributes; it only checks that their syntax is correct, as far as the
formalized description (in the DTD) is considered. So if a validator
follows some links, for example, that's completely external to
validation itself.

And for the CONTENT attribute, as well as for the TYPE attribute, the
validation process is very simple. The attribute is declared as CDATA,
which means, roughly speaking, 'any character string'. There's nothing a
validator could do to check that such an attribute has a value that
complies with HTML specifications, since the rules for those values have
not been (and could not be) described in SGML.

Thus, CONTENT="almost anything you like to type here" is definitely
valid.

And, in particular,
CONTENT="TEXT/HTML; charset:UTF-8"
is definitely valid too, but definitely incorrect. The charset
parameter, if present, must contain an equals sign "=" and not a colon
":", i.e. CONTENT="TEXT/HTML; charset=UTF-8".

The morale is that you should not expect a validator to check the
correctness of values of attributes declared as CDATA - and this covers
most attributes, as you can see from the index
http://www.w3.org/TR/html4/index/attributes.html
(where most of the notations like %Text actually stand for CDATA). Some
attributes, like align, are declared by specifying an enumerated list of
permissible values, and in _that_ case a validator checks for the
attribute value correctness.

-- 
Jukka "Yucca" Korpela, http://www.cs.tut.fi/~jkorpela/
Received on Saturday, 19 July 2003 06:47:39 GMT

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