Optional transfer to a distinct target channel

A separately identified target channel ${\mathcal{E}}_{\star }$ may obey

Both channels must have the same identified logical input and output. Direct laboratory certification sets $b=0$.

The allowance $b$ is already in half-diamond units. It is added outside the square root and is not multiplied by the input dimension, as in the specified-decoder convention of Hawk04-B CheungHawk04B (:certificate).

If a modeled decoder differs from the implemented decoder, that difference requires a converted channel allowance. Errors already inside the tested channel must not be charged again as calibration errors.