Determine if Login/logout time overlaps time period window reporting and calculate number of minutes

[JonLellelid]

I need to calculate the amount of time used on public computers in a library between the ours of 2PM and 4PM or 14:00 and 16:00. I have login timestamps that overlap both beginning and ending time period in which I am interested. If someone is logged on between 1:38PM and 2:24PM (13:38 and 14:24), I want to show the time occupied as 24 minutes. I have not found any similar examples

Is there a difference in how one calculates using 12 hour time versus 24 hour time?

Thank you.

Jon Lellelid