The authors combine concepts of synchronous programming and intensional programming for specification of real-time applications. The language Signal, based on both key elements of synchronous programming (the instantaneous and simultaneous nature of events), offers a specification formalism in which the time flow is implicit, i.e., it is dataflow oriented. Moreover, the referential time definition may be left to context; consequently, it is possible to specify some context-sensitive (intensional) processes. It is shown how local temporal and logical constraints are synthesized to exhibit the necessary and sufficient properties that a context should have to authorize a correct running. The constraints are modeled in the field of modulo 3 integers. The synthesis mechanism is presented through a detailed example.>