"M1" Position

The front brake fastens the front sun gear.
The forward brake and the forward one-way clutch regulate reverse rotation of the mid sun gear.
High and low reverse clutch connects the rear sun gear and the mid sun gear.
The low coast brake fastens the mid sun gear.
During deceleration, the low coast brake regulates forward rotation of the mid sun gear and the engine brake functions.

Fig 1: Identifying A/T Control System Power Flow Diagram (M1 Position)

Courtesy of NISSAN MOTOR CO., U.S.A.