About current input character

Hello. Maybe it's not important and may be obvious, but in the
Html-Standard spec, in the chapter:

13.2.3.5 Preprocessing the input stream

I guess the current input character should be initialized to -1, and then
before incrementing or consuming the next input character, let the current
equal to the next. I'm not sure, maybe to directly express it could be a
good idea.

Thanks.