I came across this handwritten document in a field case that I got from a friend, and it left me to ponder: what is it?

My friend Tonny gave me the field case (think briefcase but much more rugged), and inside the case was a metal plate (it was actually installed in the case, secured with screws) with holes in it (some square, some round), and this sheet of paper.

Can you decipher this page? Are these instructions? Are they parameters? Are they meant to designate connections when wiring?

My curiosity has the best of me!

handwritten document (Photo by John Falcon)

So, what is it?