The Heybrook protractor has grids for both null points allowing adjustment of both overhang and offset angle. This is what makes it universal.
However, unlike the more usual Baerwald type which is optimised for the lowest peak distortion for IEC groove radii, Heybrook chose slightly different null points. These result in an alignment somewhere between Stevenson and Baerwald.
The orange trace in this graph shows a comparison between the alignments.http://www.vinylengine.com/tonearm_alig ... =calculate