"D1 " Position

The forward brake and the forward one-way clutch regulate reverse rotation of the mid sun gear.
The 1st one-way clutch regulates reverse rotation of the rear sun gear.
The 3rd one-way clutch regulates reverse rotation of the front sun gear.
During deceleration, the mid sun gear turns forward, so the forward one-way clutch idles and the engine brake is not activated.

Fig 1: Power Transmission Diagram "D1 " Position

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