IMO, this is twaddle.
Actually this immediately struck me as the sort of thing you see on an April Fool's joke. You know, the snippet of information that should give the game away but most people will overlook. It's put there so the purveyor of the joke can point his finger and do the Nelson Muntz "Ha Ha" at you afterwards for not getting the joke.
But it is typewritten. No one was using a computer keyboard then. Would have to see what typewriter was used to produce this document to know for sure what that O/0 is/