If ``return'' is entered to amend just the spacing (and right border), the following prompt is presented (as in #19.5 and #19.6 above):
basin spacing, % of 1/2 screen
x spacing (default 30): y (default 30):
select right border as % of x spacing (default 50.0): (values shown are examples)
Enter the new spacing according to the polar co-ordinate scale, first x, then y. Remember that the screen is 200 units wide and 200 units high. Enter the new the new right border as a percentage of the x-spacing. The new values become the defaults until amended again.