If you use the standard clarion time fields, the time is calculated in 100th of a second and automatically calculates the time of day. Just use a time picture token (i.e. @t3) and it will display the am/pm for you based upon the correct time. So if the clarion time field is represents what would be 11AM (which would be I believe around 3,960,000 internally), and you add 2 hours (2 hrs * 60 min/hr * 60 sec/min * 100 = 720,000) then the time field internally is 4,680,000. Using your T3 token that would now show 1PM. All you need to do is when the duration is entered by the user (i.e. 2 hours), multiple it by the above formula and add it to your start time and the result is your end time. We use this formula all the time in all of our clarion and NT web apps.