Duration: P1Y2M3DT10H30M is 37017000 seconds Seconds: 37017000 is P1Y2M3DT10H30M duration Duration: -P120D is -10368000 seconds Seconds: -10368000 is -P4M duration Seconds: 1495825443 is P47Y5M7DT19H4M3S duration Duration: P47Y5M7DT19H4M3S is 1495825443 seconds Add should be PT0S: PT0S Subtract should be PT0S: PT0S