Returns the result of subtracting one xs:dayTimeDuration from another.
xs:dayTimeDuration values.op:subtract-dayTimeDurations( $arg1 as xs:dayTimeDuration,$arg2 as xs:dayTimeDurationxs:dayTimeDurationThe function returns the result of subtracting the value of $arg2 from the
value of $arg1. The result is the xs:dayTimeDuration whose
length in seconds is equal to the length in seconds of $arg1 minus the
length in seconds of $arg2.
For handling of overflow, see .
The expression op:subtract-dayTimeDurations(xs:dayTimeDuration("P2DT12H"),
xs:dayTimeDuration("P1DT10H30M")) returns xs:dayTimeDuration('P1DT1H30M').
Either duration (and therefore the result) may be negative.