event-flag-number

    OpenVMS usage:ef_number
    type:         longword integer (unsigned)
    access:       read only
    mechanism:    by reference

    Event flag number to be deallocated by LIB$FREE_EF. The event-
    flag-number argument is the address of a signed longword integer
    that contains the event flag number, which is the value allocated
    to the user by LIB$GET_EF or LIB$RESERVE_EF.