Nowadays the difference between exhibition and 'real' event is crystal clear. We know the only tournaments that matter are the ATP ranking events (and Davis Cup). We know not to read too much into exhibitions nowadays. But I'm not sure whether we have the same clarity about the 70s and 80s. I get the feeling not all exhibitions were unimportant e.g. the challenge matches of 1975. The other thing is I don't think the whole concept of ATP points was that important, especially in the 70s but even into the early 80s. It's well known the computer used to get the rankings wrong, but nowadays the computer rankings are very good and are taken much more seriously. So when a player in the 70s and 80s entered a tournament with no computer points, I'm not convinced this meant the tournament didn't matter. So how accurate are our official head to heads and official tournament wins from the 70s to 80s?