-- Ext.Ray= external ray. "1/7 ; 50" means "angle 1/7 and depth 50 w.r.t. zz + c coordinate".
-- Eq.Pot= equipotential curve. "0.2 ; 20" means "potential 0.2 and sharpness 20 w.r.t. zz + c coordinate".
-- What is special in this version of OTIS is that we can extract the data of external ray of the Mandelbrot set in the text area named "ExtRay Data". For example, if you press "Ext.Ray:", then the two external rays (of angle 1/7 w.r.t. zz+c coordinate) will be drawn. In addition, in the text area, we have a data of points of two external rays drawn in the Mandelbrot set window. To get the whole data, put a mouse cursor to the text area, then Ctrl+A, Ctrl+C. Then paste it to a text file.