15.64.45  PROMPT 

SET    PROMPT    [MAIN|PAUSE]   [ERASE]   [TOP]   [BOTTOM]   [BELL]   [nn]
          ["prompt_string"]

This sets the current prompt string with a maximum of 80 characters.  If a
null or blank string is used, then there is no prompt.  If  a  prompt  has
imbedded  blanks it must be enclosed in quotes.  The prompt string remains
the same until a new one is selected.
     1.  MAIN - Is the main prompt string.
         (Default:"TD:")
     2.  PAUSE - Is the prompt string used when a NEW PLOT is started.
         (Default:"PAUSE:")
     3.  ERASE  -  The  prompt  erases  the  screen (ANSI terminal).  This
         erases text from a VT-1xx/2xx compatible terminal.  This does not
         erase  TEKTRONIX  graphics,  but  REGIS  graphics will be erased.
         This must be precede the string.
     4.  TOP - The prompt is at the top of the screen (ANSI terminal).
     5.  BOTTOM  -  The  prompt  is  at  the  bottom  of  the screen (ANSI
         terminal).
     6.  BELL - This rings the bell for each prompt.
     7.  nn - This inserts a control character (0-255) into the string.
     8.

This  command  is useful for controlling the prompt for different types of
terminals.  On some terminals you can control the position of the  prompt,
so  that it will not interfere with the plot, while on others, you may not
want any prompts.