Michael Kay wrote:

  Hi,

> I think c1 was intended as a range variable
rather than an
> actual chapter name - though I can't be sure.  Certainly it
>
looks to me as if "a" is intended as a range variable

  Interesting, I didn't
think about that.  After OP's email,
I thought 'c1', 'a' etc. were introduced
only to make the query
definition easier to read.  But I might be wrong, of
course.

> I don't think I can correct it, however, without a better
>
formulation of the requirement.

  Indeed.

  Regards,

-- 
Florent Georges
http://fgeorges.org/