The OpenVMS Terminal Fallback facility (TFF) provides a table-
       driven character conversion for terminals. The conversions are
       transparent to the application  (unnoticed  by the application
       software  unless  explicit  inquiries are made).  TFF can also
       perform compose character emulation on input. Furthermore, you
       can control which terminal keys are auto-compose keys.

       One of  the  applications  of  TFF  is  to  allow  users  with
       National  Replacement  Character  (NRC)  set  terminals to use
       software  developed  with  the DEC Multinational Character
       Set (MCS). MCS is essentially the ASCII character set plus 128
       characters currently  used  by  owners of NRC terminals around
       the world.

       You can use TFF functions  through Terminal  Fallback  utility
       (TFU) commands.

       More on-line  help  is  available  from  the Terminal Fallback
       utility. To invoke TFU enter the following command in response
       to the DCL prompt:

       $ RUN SYS$SYSTEM:TFU

       The utility responds with the prompt:

       VAX/VMS Terminal Fallback Facility (TFF)
       TFU>

       After you invoke TFU, you can enter HELP or any of the
       TFU commands.