Back in the days of the pdp11/dec10 product line cards made like this were the schwag you got at DECUS meetings with the instruction set on them. I've still got one from systime, a British value add reseller, and a pdp11 one from digital.
Then emacs and vi and shell commands for Unix. Then pdf files started to appear to print at home.
The big problem for Europeans back then: assumed US/legal paper size.