time1

    OpenVMS usage:date_time
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by reference

    First time, from which LIB$SUB_TIMES subtracts the second
    time. The time1 argument is the address of an unsigned quadword
    containing this time. The time1 argument must represent a later
    or equal time or a longer or equal time interval than time2. The
    time1 argument may be either absolute time or delta time as long
    as time2 is of the same type. If time1 and time2 are of different
    types, time1 must be the absolute time.

 time2

    OpenVMS usage:date_time
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by reference

    Second time, which LIB$SUB_TIMES subtracts from the first time.
    The time2 argument is the address of an unsigned quadword
    containing this time. The time2 argument must represent an
    earlier or equal time or a shorter or equal time interval than
    time1. The time2 argument may be either absolute time or delta
    time as long as time1 is of the same type. If time2 and time1 are
    of different types, time2 must be the delta time.

 resultant-time

    OpenVMS usage:date_time
    type:         quadword (unsigned)
    access:       write only
    mechanism:    by reference

    The result of subtracting time2 from time1. The resultant-time
    argument is the address of an unsigned quadword containing the
    result. If both time1 and time2 are delta times, then resultant-
    time is a delta time. If both time1 and time2 are absolute times,
    then resultant-time is a delta time. If time1 is an absolute time
    and time2 is a delta time, then resultant-time is an absolute
    time.