MCOPY

        [MRTCAL\]MCOPY [IN|CURRENT] /FILE IndexFile

    Copy the named index (default current) from memory to the given file  to
    disk.  Any  pre-existing  file  is  overwritten, except that you can not
    overwrite one of the input index files involved during this operation.

    This command is useful for a few main purposes:
      - extract a subset from an index file, by combining the commands INDEX
        OPEN, MFIND (with criteria), and MCOPY,
      - merge  several  index  files,  by combining INDEX OPEN, INDEX APPEND
        (repeated), MFIND, MCOPY,
      - convert an old format file to latest format, simply by using INDEX
         OPEN, MCOPY IN.