I found this in a medical textbook when I was researching What’s Inside Enzyte for Wired. It’s used by doctors for categorizing all sorts of genito-urinary maladies that center around the penis. Patients would be typed as A4, B2, C1, and so on. 
Impotence researchers obviously centered on the J series of drawings.

I found this in a medical textbook when I was researching What’s Inside Enzyte for Wired. It’s used by doctors for categorizing all sorts of genito-urinary maladies that center around the penis. Patients would be typed as A4, B2, C1, and so on. 

Impotence researchers obviously centered on the J series of drawings.