Re: types of conformance statements (was Re: [css3-background] clarify which properties in this module apply to ::first-letter and ::first-line)

On Wed, Mar 28, 2012 at 1:52 PM, L. David Baron <dbaron@dbaron.org> wrote:

> On Wednesday 2012-03-28 19:32 +0800, Kang-Hao (Kenny) Lu wrote:
> > I never understand the logic used in the specs. So when a sentence (e.g.
> > the #-referenced one) is not tagged with a MUST or SHOULD, is this by
> > default a MUST? And would adding a SHOULD/MUST here help? (is
> > SHOULD/MUST stronger than a MAY if there's conflict?)
>
> By default it doesn't affect conformance; it's a statement of fact
> or a definition.  For it to affect conformance it needs to be
> incorporated by a sentence with a conformance requirement (must,
> should, etc.).
>
> That said, many CSS specs (including CSS 2.1) aren't very good about
> expressing conformance requirements where they ought to do so.
>
> For more detail, see http://ln.hixie.ch/?start=1140242962&count=1 .


A minor point of disagreement with David if I read above correctly:
definitions indeed do affect conformance, and, in most specs, definitions
constitute the majority of normative text;

e.g.,

SPEC: {Definitions, Requirements}

Definitions:
D1: D2 D3
D2: D2a D2b
D3: D3a D3b
...
Requirements:
X [implementation, content, etc.] MUST satisfy D1

none of D1..D3b.. need use MUST, SHOULD, etc., but they still play a
normative and principal function in defining the SPEC and in defining
conformance