Public figures are usually known by their initials when their surnames are too long for the average newspaper headline. Thus, taking presidents of the U.S.A. for example, we have FDR, Truman, Ike, JFK, LBJ, Nixon, Ford, Carter, Reagan, Bush, and Clinton. Ok, so "Ike" is not a set of initials, but it does have three letters. And, ok, so "Johnson" has as many letters as "Clinton," but the former's nickname was already "LBJ."