As already mentioned in Sect. 2.4, the information flow in a SRB system is usually in a forward direction, i.e. from the inputs to the outputs of the rule base, but sometimes there may also be information flow in a backward direction, i.e. from some outputs to some inputs. This FB may be as simple as an identity mapping line whereby an output is fed back unchanged directly into an input. In other cases, the FB may be of a more complex nature whereby the output passes through a feedback rule base (FRB) that changes it before it is fed into the corresponding input.