That restriction was for the simple case (no other numbering).
I carried on to try to explain that there is a problem with using a named
List Template that is *also* linked to a style. It will work in a single
document (and when I first tried it I thought it was a Eureka moment <g>),
but I ran into difficulties as soon as I tried to copy numbered paras and
styles between docs (including update styles from template, even with code
fixes). IIRC, Word drops the name of a List Template linked to a style where
that name is already in use in the target document. You end up with
different effects depending on whether you are copying the styled para
and/or the LISTNUMs, and the end result is that the numbering sequence
'connection' between style and LISTNUM made via the name can get broken.
My line of reasoning was thus - more than one sort of numbering (a 'blizzard
of styles' or just one or two) means you can't use the default (unnamed)
LISTNUM, as you may pick up the wrong sequence (dependent on position). You
are therefore forced to name the LISTNUM, which introduces the problem
above, blocking it as a reliable solution. However, I believe you can use
*all* named LISTNUMs (hence the suggestion to insert in the "Annex" title),
because the copy and paste problem doesn't apply (the field is copied but
not the List Template, so Names are left alone).
It may be that there are circumstances or Word SRs in which the name
'connection' can be made to work of course, but it looks like this was not a
tested or supported scenario in 2002/2003 and so I haven't felt it is
something that can be recommended.