Contaflex Lens Faux Focus Ring?

I have 2 Contaflex lenses -- the 35/3.2 and the 115mm Pro Tessars. Both have a ring at the base that rotates and has distance markings but the ring just turns 'round and 'round and does nothing that I can see.

I could find no explanation in manuals or elsewhere for the purpose of this ring. Anyone know what it is for?

Isn't it the depth of field scale?

I looked at a couple of pics, and yes, they are DOF-scales. The wide and tele convertible lenses for the Retina c/C and some Retina Reflex cameras also have these DOF-scales. These lenses don't have focusing mechanisms because they are only the front components and need to focus as a unit with the rear components that are permanently in the camera and the same for all lens combinations. So the focusing mechanism is in the camera itself and the DOF-scales have to be single purpose rings on the interchangeable front lens components.

Thanks!