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Re: [CSS21] Section 6.1.3

From: Ian Hickson <ian@hixie.ch>
Date: Thu, 25 Aug 2005 14:40:17 +0000 (UTC)
To: Craig Northway <craign@cisra.canon.com.au>
Cc: www-style@w3.org
Message-ID: <Pine.LNX.4.62.0508251419250.3279@dhalsim.dreamhost.com>

On Thu, 25 Aug 2005, Craig Northway wrote:
> > 
> > No, it's not optional, but that is because section 3.2 requires that 
> > user agents implement CSS consistent with the descriptions laid out in 
> > the spec, including section 6.
> I do not think this is clear enough. I think that each statement 
> throughout the specification that requires conformance from a user agent 
> should use terminology that indicates this.

This is the case.

CSS is not defined in terms of functional steps ("do this then do this 
then do this"), it is defined in terms of a model ("it is this"), an 
implementation for which must then be found.

Most of the CSS spec describes the model. The only thing a UA implementor 
has to do to claim conformance is be consistent with the model.

> The QA Framework: Specification Guidelines
> (http://www.w3.org/TR/2005/REC-qaframe-spec-20050817) requirement 7 states:
>          Use a consistent style for conformance requirements and
>          explain how to distinguish them
> Requirement 8 states:
>          Indicate which conformance requirements are mandatory, which
>          are recommended, and which are optional.
> Specifying in section 3.2 that a UA must conform with the rest of the 
> specification does not make it easy to distinguish conformance 
> requirements. Nor does it make it easy to determine which comments are 
> mandatory, recommended or optional.

It should be pretty clear; if something describes the model, it's 
something the implementation has to be consistent with. Certain things are 
explicitly stated as being outside the model ("The behavior of the 'auto' 
value is user agent-dependent") and RFC2119 terms are used when 
conformance criteria outside the model are required ("but should cause a 
scrolling mechanism to be provided for overflowing boxes").

> > Specifically, in the case of 6.1.3, the two "must" requirements that 
> > apply are "For each element in a document tree, it must assign a value 
> > for every applicable property according to the property's definition 
> > and the rules of cascading and inheritance" and "A user agent that 
> > renders a document with associated style sheets must respect points 
> > 1-5 and render the document according to the media-specific 
> > requirements set forth in this specification", which are list item 4 
> > and the third bullet point in section 3.2 respectively.
> > 
> > Please let us know if that addresses your concern.
> Where are these musts you indicate that apply to section 6.1.3? they 
> are not linked to section 6.1.3.

Section 3.2.

If this does not address your concern please explain how the CSS spec 
should be rewritten to use a different conformance model. It is not clear 
to me how we can require conformance to a model without using the 
mechanism used by CSS2.1. For example, take margin collapsing:


Could you rewrite that section in a way that would satisfy your request?

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Thursday, 25 August 2005 14:40:31 UTC

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