The term “representation”, like function, is frequently used in two related but different senses. Sometimes it refers to the mechanism, or sign vehicle, which does the representing, as in “a stop sign is a representation”. Sometimes the term refers to the act or process of representing, in which case there needs to be someone or something interpreting the representing object. The distinction is significant because the question arises in philosophy as what counts as a representation. If you put information on a disk and shoot that into space (as has happened), does that disk count as a representation, assuming there is in fact no intelligent life out there, and so no one for the disk to represent “to”?
For our purposes we will say representation is the act of representing, and that a vehicle designed for the purpose of representing is an affordance of representation, and that representation happens when said vehicle is used/perceived as a representing vehicle.
To express this in the current framework we have to describe two separate processes (tasks). The first task is the process of creating the representing vehicle, which is the output of the task. This vehicle will have mutual information as determined by the computational functions inherent in the creating mechanism and its inputs. We call this vehicle a representing vehicle if the sole purpose of the vehicle-crating mechanism is to generate a vehicle that carries that mutual information to be used in representation.
The second process involved in the “representation” is the one which takes the representing vehicle as input and generates some output which is valuable relative to the mutual information associated with the vehicle. We would call this an interpretation of the representation. Note there could be multiple processes which respond to the same vehicle. The “meaning” of the representation is determined by the mechanism which is doing the interpretation.