LBR$GET_INDEX searches through the specified index for keys that
    match the match_desc argument. Each time it finds a match, it
    calls the user routine specified by the routine_name argument. If
    you do not specify the match_desc argument, LBR$GET_INDEX calls
    the user routine for every key in the index.

    For example, if you call LBR$GET_INDEX on an object library with
    match_desc equal to TR* and index_number set to 1 (module name
    table), then LBR$GET_INDEX calls routine_name for each module
    whose name begins with TR.