The result of adding a duration to a time, or of subtracting a duration from a time, is itself a time. Any overflow or underflow of hours is discarded, thereby ensuring that the result is always a time.
If a duration of hours is added or subtracted, only the hours portion of the time is affected. The minutes and seconds are unchanged.
Similarly, if a duration of minutes is added or subtracted, only minutes and, if necessary, hours are affected. The seconds portion of the time is unchanged.
Adding or subtracting a duration of seconds, of course, affects the seconds portion of the time, and potentially the minutes and hours.
Time durations, whether positive or negative, also can be added to and subtracted from times. The result is a time that has been incremented or decremented by the specified number of hours, minutes, and seconds, in that order.TIME1 + X, where X is a DECIMAL(6,0) number, is equivalent to the expression: TIME1 + %DURHOUR(%HOUR(X)) + %DURMINUTE(%MINUTE(X)) + %DURSEC(%SECOND(X))