Type Certification
What things can be varied under a given type cert?
For example, I assume engine power can't be, but actual engine? i.e. Would you have seperate type certs to cover each engine supplier?
Do the rules vary from authority to authority?
Do authorities vary in what constitutes a type? e.g. Can you have a scenario where aircraft A & B are viewed as two types by one authority, and one type by another?