Qualifiers

/DATA_CHECK
      /DATA_CHECK[=(READ,WRITE)]
      /NODATA_CHECK

   Determines whether EXCHANGE performs a second operation after
   every I/O operation to verify that the data was correctly
   transferred. If you specify /DATA_CHECK=WRITE, after every
   write operation EXCHANGE rereads the data that was just written
   and compares it with the original data. If you specify /DATA_
   CHECK=READ, EXCHANGE reads each block of data twice and verifies
   that both read operations received identical data.

   It is usually more efficient to use the /DATA_CHECK option on
   the DCL command MOUNT than to use the option on the EXCHANGE
   command MOUNT. If you mount a device with the DCL command
   MOUNT/FOREIGN/DATA_CHECK, OpenVMS can use features in the
   device hardware and device driver to perform the redundant I/O
   operations.

   The RX01 and RX02 diskette drives do not contain the necessary
   features for the operating system to perform data checking. If
   you use the DCL command MOUNT/DATA_CHECK with a diskette, the
   system is unable to perform data checking (no warning message
   is displayed). EXCHANGE is able to recognize, however, that a
   diskette was mounted with the data checking option; in this case,
   EXCHANGE performs the software data checking internally, even if
   you have not specified an explicit MOUNT/DATA_CHECK command.

   If you specify the /DATA_CHECK qualifier without an option, the
   default is /DATA_CHECK=WRITE.


/FOREIGN
   Indicates that the volume is not in the standard format used by
   the OpenVMS operating system; that is, a magnetic tape volume
   is not in the standard ANSI format, or a disk volume is not in
   Files-11 format. The EXCHANGE command MOUNT mounts only foreign
   volumes. The /FOREIGN qualifier is the default. You must use the
   DCL command MOUNT to mount OpenVMS volumes.

   The default protection applied to foreign volumes is RWLP (Read,
   Write, Logical I/O, Physical I/O) for the system and owner. If
   you mount a volume currently in Files-11 format with the /FOREIGN
   qualifier, you must have the user privilege to override volume
   protection (VOLPRO), or your UIC must match the UIC on the
   volume.


/MESSAGE
      /MESSAGE
      /NOMESSAGE

   Controls whether EXCHANGE displays a message indicating that the
   volume was mounted. The default is determined by the /MESSAGE
   qualifier specified with the EXCHANGE command when EXCHANGE was
   invoked.


/VIRTUAL
   Mounts a Files-11 file as a virtual device. When you specify
   /VIRTUAL, the MOUNT command requires two parameters. The first
   parameter is a device name assigned as the name of the virtual
   device. The second parameter is the name of the Files-11 file
   that is the image of a foreign volume.


/VOLUME_FORMAT
      /VOLUME_FORMAT=option

   Defines the physical format of the volume to be processed.


/WRITE
      /WRITE
      /NOWRITE

   Controls whether the volume can be written. You can specify
   /NOWRITE to protect files by providing read-only access.
   Specifying /NOWRITE is equivalent to write-locking the device.

   The default is /WRITE. If /WRITE is specified (either explicitly
   or by default) and the volume itself is write-locked, EXCHANGE
   displays a message to inform you that the volume is write-locked.