Three columns...In timeOut TimeTotal Time (calculate based on in and out entered) if( HasValue(spec1b) & HasValue(spec1a) ) then// compute time difference in minutesvar TimeDiff = (Time2Num(spec1b.formattedValue, "h:MM A") - Time2Num(spec1a.formattedValue, "h:MM A")) / (1000 * 60)// truncate to hoursvar HourDiff = Floor(TimeDiff / 60)// get minutes less than 60var MinDiff = Mod(TimeDiff, 60)// build fomatted dispaly stringConcat( Format("Z9", HourDiff), ":", Format("99",MinDiff) )else// if any values missing null the outputnullendif