Duration: P1Y2M3DT10H30M is 37017000 seconds Seconds: 37017000 is P1Y2M3DT10H30M duration Duration: -P120D is -10368000 seconds Seconds: -10368000 is -P4M duration Seconds: 1493402472 is P47Y4M9DT18H1M12S duration Duration: P47Y4M9DT18H1M12S is 1493402472 seconds Add should be PT0S: PT0S Subtract should be PT0S: PT0S