2 UNIT
  Syntax: UNIT lun
   where: lun  is a new input unit

  WARNING: Do not  use this command  in Mn_Fit. Use  the EXEC command to
  read in commands from a file.

  Redefines  the input unit  5 [ISYSRD].  You get a  prompt `MINUIT>' or
  `OPER>' as  long as  ISYSRD=5. When you  switch to  `ISYSRD.NE.5' (for
  which you have to make an `ASSIGN' statement before running your job).
  You will no longer get a prompt. Unit 5 is understood to be a terminal
  (also in batch mode).

