form. The key to our choice of morphism lies in understanding internal actions as a pair of unspeci ed synchronising actions, hidden from the environment. One may like to think of pre xing as syntactic sugar for a:(a! k a?P ): We consider what e ects specifying a name, a, for these actions, and allowing them to be seen by the environment, has; call this speci ed synchronising pair a, so one mig...