signal_vector

    OpenVMS usage:arg_list
    type:         longword (unsigned)
    access:       modify
    mechanism:    by reference
    Signal vector. See the HP OpenVMS System Services Reference
    Manual for information about the signal vector passed to a
    condition handler.

 mechanism_vector

    OpenVMS usage:arg_list
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    Mechanism vector. See the HP OpenVMS System Services Reference
    Manual for information about the mechanism vector passed to a
    condition handler.