What are the various grafting techniques?

Onlay grafting where the graft is placed lateral to the remaining TM and underlay grafting where the graft is placed medial to remains of TM after lifting up a tympanomeatal flap. Other techniques are “through graft” which is onlay posteriorly and under lay anteriorly. and “ Reverse through graft” which is underlay posteriorly and on lay anterieoly.