VMS Help MERGE, Input File Qualifier, /FORMAT, Qualifier Values  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 RECORD_SIZE:n

    Specifies the input file's longest record length (LRL) in bytes.

    The maximum longest record length that can be specified depends
    on the file organization:

    Sequential files          32,767
    Relative files            16,383
    Indexed-sequential files  16,362

    These totals include control bytes for variable records with
    fixed-length control (VFC) format.

 FILE_SIZE:n

    Specifies input file size in blocks. The maximum file size
    accepted is 4,294,967,295 blocks.