Call the SOR$RETURN_REC routine to release the sorted or merged
    records to a program. Call this routine once for each record to
    be returned.

    SOR$RETURN_REC places the record into a record buffer that you
    set up in the program's data area. After SORT has successfully
    returned all the records to the program, it returns the status
    code SS$_ENDOFFILE, which indicates that there are no more
    records to return.

    Some of the following condition values are used with different
    severities, depending on whether SORT/MERGE can recover. Thus,
    if you want to check for a specific status, you should use
    LIB$MATCH_COND.