On Thu, 30 Apr 2009 09:13:55 +0100, "David Biddulph" <groups [at]
biddulph.org.uk wrote:

If you want to use 12 hour format, then of course you need to include the AM
or PM. That's what 12 hour format is.


People entering start times or stop times typically do not want to futz
around with any more than the least sized set of keypresses. So most
would opt for hh:mm entry, which means that one MUST use 24 hr format for
a sheet set up for quick entry.

So you will see time tracking where 24 hr format is utilized more often
than forcing a person to enter long format time declarations.