This document discusses transgressive-regressive (T-R) sequence stratigraphy. It summarizes the limitations of previous definitions of sequences that utilized different bounding surfaces. A type 1 sequence uses a subaerial unconformity and correlative conformity placed at the start of base level fall, including part of the unconformity within the sequence. A type 2 sequence also uses the subaerial unconformity but places the correlative conformity at the end of base level fall, which is difficult to objectively identify. Galloway's genetic stratigraphic sequence uses maximum flooding surfaces but includes the subaerial unconformity within the sequence. To overcome these issues, Embry and Johannessen defined a T-R