context

    OpenVMS usage:context
    type:         longword (unsigned)
    access:       write only
    mechanism:    by reference
    Value identifying the data stream that DCX$MAKE_MAP maps. The
    context argument is the address of a longword containing this
    value. DCX$ANALYZE_INIT initializes this value; you should not
    modify it. You can define multiple context arguments to identify
    multiple data streams that are processed simultaneously.

 map_addr

    OpenVMS usage:address
    type:         longword (unsigned)
    access:       write only
    mechanism:    by reference
    Starting address of the compression/expansion function. The map_
    addr argument is the address of a longword into which DCX$MAKE_
    MAP stores the virtual address of the compression/expansion
    function.

 map_size

    OpenVMS usage:longword_signed
    type:         longword (unsigned)
    access:       write only
    mechanism:    by reference
    Length of the compression/expansion function. The map_size
    argument is the address of the longword into which DCX$MAKE_MAP
    writes the length of the compression/expansion function.