Where did the name K valve or J valve come from?

Question

You see them on the older tanks but where did the name come from?

Answer 1

I believe that both the J-valve and the K-valve where listed in the New
England Divers Catalogue
as U.S Divers valves and they had the letter J & K next to them as a
reference.  New England Divers
was the first and largest retail and mail order scuba place in the
world. When people were 
the valves they would refer to them as the J or K valve in the
catalogue.  

Answer 2

They were named from the early days (1950's) of scuba.   Neither resemble a J or K on your reg attaching to the tank

Comments

Not so came from the listing in the sears catalog.