Qualifiers

/APPEND
   Opens an existing file for writing and positions the record
   pointer at the end-of-file (EOF). New records are added to the
   end of the file.

   Only sequential files allow more than one user to append records
   concurrently.

   Use the /APPEND qualifier only to add records to an existing
   file. The /APPEND and the /WRITE qualifiers are mutually
   exclusive.


/ERROR
      /ERROR=label

   Transfers control to the location specified by the label keyword
   (in a command procedure) if the open operation results in an
   error. The error routine specified for this qualifier overrides
   any ON condition action specified. If the /ERROR qualifier is not
   specified, the current ON condition action is taken.

   If an error occurs and the target label is successfully given
   control, the global symbol $STATUS retains the code for the error
   that caused the error path to be taken.


/READ
      /READ (default)

   Opens the file for reading. If you open a file with /READ, other
   users are also allowed read access to the file, but no user is
   allowed write access. If you open a file with /READ/WRITE, no
   other users are allowed access while the file is open. If you
   specify the /READ qualifier without the /WRITE qualifier, you
   must specify an existing file.


/SHARE
      /SHARE[=option]
      /NOSHARE (Alpha/Integrity servers only)

   Opens the specified file as a shareable file to allow other users
   read or write access. If you specify the /SHARE=READ qualifier,
   other users are allowed read (R) access to the file, but not
   write (W) access. If you specify the /SHARE=WRITE or the /SHARE
   qualifier with no option, users are allowed read and write access
   to the specified file.

   To open a file with no shared access, specify /NOSHARE or use
   OPEN/READ/WRITE.


/WRITE
   Opens the file for writing. The following restrictions apply to
   the /WRITE qualifier:

   o  Use the /WRITE qualifier to open and create a new, sequential
      file. If the file specification on an OPEN/WRITE command does
      not include a file version number, and if a file with the
      specified file name and file type already exists, a new file
      with a version number one greater than the existing file is
      created.

   o  Use the /READ qualifier with the /WRITE qualifier to open an
      existing file. While the file is open, no other user will have
      access to it. When the file is first opened, the pointer is
      positioned to the beginning of the file. (This differs from
      OPEN/APPEND, which positions the pointer at the end of the
      file.) You cannot use OPEN/READ/WRITE to create a new file.

   o  The /WRITE and the /APPEND qualifiers are mutually exclusive.