I'm reading an article on typography and it is suggested at one point that a certain heading should have "Small Caps, spaced generously at 75".
What does that number, 75, represent?
I would assume tracking (or letter spacing).
In Adobe software that is measured as 1/1000 of an em (so "75" is 0.075 em). In QuarkXPress it is measured as 1/200 of an em (so "75" is 0.375 em) and there are probably other variations (you can set CSS
letter-spacing in whatever unit you like, for example)... So without knowing the context in which it is being talked about that number is a bit ambiguous.