"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 "D1" Position Diagram