-f_authfile

   Specifies the name of the X authority file. Version numbers
   are not allowed. If a display device is specified on the
   command line, xauth will use the X authority file referenced
   by the display device. Otherwise, xauth will use the default X
   authority file used by client applications. This file is the X
   authority file referenced by the DECW$DISPLAY display device, the
   DECW$XAUTHORITY logical, or SYS$LOGIN:DECW$XAUTHORITY.DECW$XAUTH.