what is experimental film?

While I can understand why Camper's article is helpful in defining the over-arching characteristics of experimental film, I find that it reads too much like a rule book.  Obviously many of these points can be contested, and the concept of over-arching characteristics of experimental film seems strange, since there really isn't a good way to define the mode. In an academic setting though, I do appreciate having this passage as a reference, as it is often hard to define whether or not a film could be considered avant-garde or experimental if you don't know which traits to look out for. Someone who may not be familiar with this mode of film-making would find this reading extremely helpful.