Exactly. Also, the DF 7x40 has a couple of other weird accessories. In the left tube there is a specially treated element that serves as an IR detector. Slide it into the field of view by turning a knob and if you happen to be looking at an active IR source (eg. IR lamp or active night scope) at night you'll supposedly see a glowing spot. Haven't tried it out yet and I'm not sure the detector still works at all because of the limited shelf life. But it's there.

#2, on the right tube there's a dovetail attachment with a small glass window for a special illuminator. Basically a tiny flashlight made specifically for the DF 7x40. When attached to the binoculars you can use it to illuminate the reticle.

All in all, those may be some fairly useless features these days, at least from a civilian point of view, but back in the 1970's it must've been state-of-the-art technology.