Noon to midnight formula help

[Nepboard]

I'm trying to write a custom formula to only show records that happened between noon and midnight over a specific date range. I have no problem with the date range but the time thing is killing me. The start time is in the ({Trips.calltime} table. The ending time is located in the {Trips.atstime} table. Thanks!

[JaganEllis]

What does 'happened' mean? Started on/after 12pm? Is the end time relevant?
Try the Time function, e.g.

and time({trips.calltime}) >= time(12,0,0)