Functional architecture, or equivalently functional analysis, intends to describe precisely the different functions of a system and their relative interactions. The core motivation of functional architecture is to start understanding and specifying in details the system, but only in terms of behaviors – i.e. in other terms, to understand and specify what does the system – and not of concrete structure, i.e. in its functional nature … as one would have easily guessed! It is indeed important to have first a functional description of a system, and not to dig immediately in the technique, if one wants to be able to rationally manage trade-offs between different options...