library_index

    OpenVMS usage:longword_unsigned
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    Library control index returned by the LBR$INI_CONTROL routine.
    The library_index argument is the address of the longword that
    contains the index.

 txtrfa

    OpenVMS usage:vector_longword_unsigned
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    Record's file address (RFA) of the module header for the module
    you want to access. The txtrfa argument is the address of a 2-
    longword array containing the RFA. You can obtain the RFA of a
    module header by calling LBR$LOOKUP_KEY or LBR$PUT_RECORD.