/KEY=(POSITION=n,SIZE=n)

    Searches the records of a file (beginning at the specified
    position) for the length of the specified size.

    You can specify the POSITION keyword value as 1 to 32,767. The
    first byte in a record is considered position 1.

                                   NOTE

       The /KEY qualifier must appear before the file name, or
       after the specified search string. If the qualifier is
       placed between these parameters, it is ignored.