The definition of a selfbow has been pretty broad in the shoots I've been to that have a selfbow class. Most consider any bow without glass or carbon laminations to be eligible to shoot in the selfbow class. I've seen folks shoot everything from true straight limbed selfbows to r/d bamboo backed osage bows in what have been called selfbow classes. I don't know of any official equipment definitions for a selfbow class,like IBO or ASA. I believe most clubsdevelope their own standards as to what is or is not a selfbow.