bug#6493:

["Drew Adams" <drew.adams@oracle.com>]

> > Something that should be mentioned in the doc strings is 
> > the following:
> >
> >    The next two functions signal an error if the mark does not point
> >    anywhere. If Transient Mark mode is enabled and
> >    `mark-even-if-inactive' is `nil', they also signal an 
> >    error if the mark is inactive.

Why should that be mentioned?
What important problem or use case would we be pointing out?

> Can we simplify that to just say that they signal an error if the
> region is not active? (The region-* commands are somewhat specific, so
> it's reasonable to suppose that the programmer knows what he's doing
> or can lookup the docs.)

I have no real objection to a clear statement of the error handling.
In general it is a good idea to mention important error cases.

But I do not think it is necessary to mention error handling at all for these
doc strings.  In this case, saying more is saying less, and likely to just add
confusion.

It's pretty obvious that a numerical comparison needs to be done to determine
the smaller/larger of point and mark, and it's similarly obvious that if the
numerical value of one of them (mark) cannot be determined then an error would
be raised.

That does not follow _logically_ - we could return the other value (point is
numeric) or some special value to indicate this condition, but raising an error
seems like common sense and what users would expect.  I see no reason to add
info about the error handling.