Technical 3 spring frame?

I was reading a post yesterday and the OP mentioned something about a “3 spring frame” he found it had. I was going ask what that meant, but lost service on my phone at the time and know can’t find the thread.
Seemed he was referring to a factory frame, not adding parallel leafs to say a 36 Ford.
Been bugging me all night at work

 

https://www.jalopyjournal.com/forum/threads/three-springer-3-springer-picture-thread.583579/

 

I see, so traverse is the rear, two up front.

 

Some 3 Springers were rough as a cob. I love them.
Sometimes they took a frame and turned it around and used the rear as the front. Sometimes they used quarter ellipticals. Sometimes the transverse was on the front but usually it was the rear.
There's lots of lee way in a 3 Springer.....

These are definitely not a "Homogenized Hot Rod!