The Update service allows you to modify the contents of an
    existing record in a file residing on a disk device.

                         RAB64 USERS (ALPHA ONLY)

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

    Format

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