Here is Jost Ammon’s version, which I found as an online version of the whole set of woodcuts http://www.fulltable.com/VTS/aoi/a/amman/jam.htm
Notice that the man sawing has switched legs to hold down the stock. There’s numerous other differences, sort of a child’s game to compare & contrast.
I imagine there are more illustrations of this type of square. Although I have never made one, I bet it functions like the miter square I discussed previously. https://pfollansbee.wordpress.com/2009/03/12/miter-squares-then-now/
A reminder that there is a search function on the right-hand column on this blog; sometimes I use it to see what I have said before…otherwise I might come up with what I think is a brilliant idea, only to find out that I already did it!