18.35  TDVAX_PLOT 

     CALL TDVAX_PLOT
This  will set up your terminal as the default device, provided the symbol
PLOT_TERM is correctly set.  Normally it is set when you  log  in  so  you
usually do not need to worry about it.

If  this routine is not called, you must call TDSET and specify the device
to use in plotting.