Re: COL and COLGROUP

On Thu, 14 Jan 1999, L. David Baron wrote:

> The wording of the spec and the DTD seem to disagree over COL and
> COLGROUP elements.

Generally, I think it is obvious that a DTD has precedence over
any prose statements, in matters of syntax. (But _comments_ in
a DTD have no authoritative meaning, especially since they are
typically short, therefore subject to misunderstandings and
varying interpretations.)

> Section 11.2.4 of html40 [1] says:
- -
>    [COL elements] may appear inside or outside an explicit column group
>    i.e., COLGROUP element).

This could be interpreted in a manner which allows constructs which
are not valid (i.e. do not conform to the DTD). Thus, for future
specifications, a more explicit statement could be considered.

But the statement does not disagree with the DTD. It just needs to
be read with the implicit addition "subject to any restrictions
that might be imposed elsewhere" (which is an addition we must
imply for all prose statements in a specification). And in fact, the
relevant restriction is given in prose too, in the second paragraph of
section 11.2.4:

  A table may either contain a single implicit column group (no COLGROUP
  element delimits the columns) or any number of explicit column groups
  (each delimited by an instance of the COLGROUP element).

This seems to be as definite as one can say in prose in English;
the "either - - or - -" connective is normally to be understood
as exclusive or.

-- 
Yucca, http://www.hut.fi/u/jkorpela/ or http://yucca.hut.fi/yucca.html

Received on Friday, 15 January 1999 02:46:36 UTC