I have now gone through this exercise, and the resulting report appears below. You will note that I was able to find multiple uses of every general feature of the language. The only specific feature I had problems with was binary representation of terminal values. The only RFC I could find that used this representation was RFC 3018, and its usage was a bit peculiar. So I suppose if we wanted to remove something binary representation would be it. But I really don't think this is necessary or particularly useful.