What is meant by Major and Minor Surgery?

Any surgical intervention that penetrates and exposes a body cavity; any procedure that has the potential for inducing permanent anatomic (physical) or physiologic impairment and/or any procedure associated with orthopedics or extensive tissue dissection or transection.
A minor surgical procedure is one that neither penetrates or exposes a body cavity, nor induces permanent impairment of physical or physiologic function. Examples are laparoscopy, superficial vascular cutdown, and percutaneous biopsy.