Here we have Otto Šaman of Rokycany (home of Favorit) collaborating with Vladimír Mávr of Cheb (Home of ESKA) to produce a indexed design that is a clear melding of a Favorit Special with a mid-1970s Shimano Positron. The indexing mechanism is pure Positron right down to the sprung ball bearing running across the wave shaped surface - which is a bit odd given that Positron was long out of fashion by 1987.
To complete the lunacy, the outer pulley cage plate has acquired an extravagant curved chain pusher area - vaguely reminiscent of the execrable 1970 Campagnolo Gran Turismo - another design that was held in contempt by 1987.
I am indebted to a Czech speaking correspondent for the information that (like a Shimano Positron II) this design uses an unsprung parallelogram and a rigid piano wire. He also tells me that it incorporates two innovations. The first is that the wave shaped surface that controls the indexing is a replaceable part - allowing you to exchange it to change from, say, 5 speed to 6 speed indexing. The second innovation is that any bending of the piano wire is minimised by the combination of the geometry of the cable run and the controlled rotation of the outer cable stop - pleasingly reminiscent of Shimano’s own ‘Synchro-Line Mechanism’.