[css2.1] Every nonterminal should have a formal grammar specification

My earlier message about <family-name> raises this issue but I thought
it might deserve its own thread.  CSS (both 2.1 and the various level-3
modules) has a chronic tendency to define property-value nonterminals
only in prose, not with a formal syntax.  That prose tends to be
ambiguous, or at least to assume things that are never stated.

I request that the WG audit the existing specs, all of them, and add
formal syntax definitions for *every* nonterminal; and going forward,
that new proposals be required to provide these definitions.

[I don't care whether the grammar is L-anything.  I only care that it
be fully, formally, specified.]

zw