This is a proper set of instructions - obscure, uninformative, well soaked in bicycle oil and printed on paper that would be ideally suited for Long John Silver’s map of buried treasure. For the full effect they should be lightly singed at the corners.
The cartridge bearing in the guide pulley is a nice touch.
From the ‘Edition N. C/7/77’ at the bottom, it looks to me as if they were printed in July 1977.
Browse associated derailleurs.