I believe the technical term is “Schelling point”: something that people can decide on without communication. Base64 is very close to the Schelling point of Ba

I believe the technical term is “Schelling point”: something that people can decide on without communication. Base64 is very close to the Schelling point of Base62 i.e. [A-Za-z0-9], requiring only a couple more additional decisions to be made: which two extra characters to add. Unfortunately the original Base64 inexplicably got this wrong and chose + and / instead of the more sensible choice of - and _