Encapsulation of a generic data processing algorithm. A control block is connected to a set of inputs uk and to a set of outputs yk and is capable of propagating the inputs to the outputs by applying a transfer function to them. The transfer function is of the generic kind: yk+1=f(xk,uk) where xk is an state variable that is internally propagated according to an equation like: xk+1=g(xk,uk).
See the Control Block design pattern.