A simplified TIME format that is in common usage in New Zealand is H:MM as 12hr
style and excluding the AM/PM characters; e.g. 1:30 for 01:30 PM {13:30}.
In a large number of printed outputs that include times, the approximate time is
already implied, for example: school class times will likely be between 09:00AM
and 03:00PM and never between 10:00PM and 05:00AM; thus the shown time of 11:30
{without any AM or PM lettering added} for a maths class start time is never
mistaken to mean an evening session starting 1/2 an hour before midnight! As
such in our Kiwi culture, with it's usage of the 12hr clock [24hr clocks being
so rare as to be confusing to many New Zealanders] it is almost universial to
just show times in the most simple format of H:MM (12hr, no suffix).
I, personally, have been taught (by Eike Rathke) how to use simple =IF() formula
to convert enties from H:MM (24hr format) to always show as times less than
12:59 but this is an option that is completely out of the question for general
New Zealand users.
I expect that the resolution of this issue will nessesitate the modifiying of
your standard convention for seperating 12hr and 24hr time formats; ie. by the
simple inclusion or exclusion of the "AM/PM" text in the "format code", but
maybe you could use "[AM/PM]" to represent the hidden state of the AM/PM text
{or likely there is some other standard formatting code idea that I, a simple
user, know nothing of!}.

Thank you for your considerations.
Warwick F. Taylor