The Flush service writes out all modified I/O buffers and file
    attributes associated with the file. This ensures that all record
    activity up to the point at which the Flush service executes is
    actually reflected in the file.

                         RAB64 USERS (ALPHA ONLY)

       On Alpha systems, RAB64 can replace the RAB or RAB prefix
       wherever it is used with the Flush service on OpenVMS Alpha
       systems.

    Format

      SYS$FLUSH  rab [,[err] [,suc]]