Format and Protocol Languages

Historically, these start with the IBM system, FAPL which was used to specify large parts of the Systems Network Architecture. It is an extension of PL/1, to include Finite State Machines (FSM) and state transition. RSPL was developed at the technical University in Berlin to specify protocol sequences and alternate actions. ISO formed two committees to work in this area, and the two draft proposals for systems are: LOTOS is based on some firm mathematics in Temporal Logic, that allows the proof of behavior of the processes described.