This is fortunately a one off
question and basically refers to the input to and the output from the computer.
The command signal is initially
passed to the comparitor, which then compares it to
the current position of the aircraft before feeding a signal (epsilon) to the
computer.
The computer then determines the
required control deflection (betaC) to satisfy the
input.
The piloting law is thus based on the
control surface movement required (betaC) to achieve a desired change of
attitude (epsilon) .