The LBR$LOOKUP_KEY routine looks up a key in the library's
    current index and prepares to access the data in the module
    associated with the key.

    Format

      LBR$LOOKUP_KEY  library_index ,key_name ,txtrfa [, flags]

1 - Returns

    OpenVMS usage:cond_value
    type:         longword (unsigned)
    access:       write only
    mechanism:    by value

    Longword condition value. Most utility routines return a
    condition value. Condition values that this routine can return
    are listed under Condition Values Returned.

2 - Arguments

 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.

 key_name

    OpenVMS usage:longword_unsigned
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    Name of the library key. If the library uses binary keys, the
    key_name argument is the address of the unsigned longword value
    of the key.

    If the library uses ASCII keys, the key_name argument is the
    address of a string descriptor for the key with the following
    argument characteristics:

    Argument
    Characteristics        Entry

    OpenVMS usage          char_string
    type                   character string
    access                 read only
    mechanism              by descriptor

 txtrfa

    OpenVMS usage:vector_longword_unsigned
    type:         longword (unsigned)
    access:       write only
    mechanism:    by reference
    The record file address (RFA) of the library module header.
    The txtrfa argument is the address of the 2-longword array that
    receives the RFA of the module header.

 flags

    OpenVMS usage:mask_longword
    type:         longword (unsigned)
    access:       write only
    mechanism:    by reference
    The flags argument, if present and not zero, receives the type of
    key returned. The flag bits are as follows:

    Flag Bits              Description

    LBR$SYM_WEAK = 0x1     UNIX-style weak symbol attribute
    LBR$SYM_GROUP = 0x2    Group symbol attribute

    The key returned is the highest precedent definition type
    present.

3 - Description

    If LBR$LOOKUP_KEY finds the specified key, it initializes
    internal tables so you can access the associated data.

    This routine returns the RFA to the 2-longword array referenced
    by txtrfa.

4 - Condition Values Returned

    LBR$_ILLCTL        Specified library control index not valid.
    LBR$_INVRFA        RFA obtained not valid.
    LBR$_KEYNOTFND     Specified key not found.
    LBR$_LIBNOTOPN     Specified library not open.