MCOPY

        [MRTCAL\]MCOPY IndexFile

    Copy  the  current  index (from memory) to the given file (to disk). Any
    pre-existing file is overwritten, except that you can not overwrite  one
    of  the input files involved during this operation. This command is use-
    ful for two main purposes:
      - extract a subset from an index file, by combining the commands INDEX
        OPEN, MFIND (with criteria), and MCOPY, or
      - merge  several  index  files,  by combining INDEX OPEN, INDEX APPEND
        (repeated), MFIND, MCOPY.