$T(x,y)=I(x)-I(x|y)$

Note 1 to entry: The two events are particularly a message at the message source of a channel and a message at the message sink of the channel.

Note 2 to entry: The transinformation content can also be expressed as: $T(x,y)=I\left(x\right)+I\left(y\right)-I\left(x,y\right)$, where I(y) is the information content of the event y. From this follows that it is symmetric in x and y: $T(x,y)=T(y,x)$.