LOTOS is a formal specification language, designed for the precise description of open distributed systems and protocols. The definition of, so called, implementation relations has made it possible also to use LOTOS as a specification technique for the design of such systems. These LOTOS based specification techniques usually (ab)use non-determinism to achieve implementation freedom. Unfortunately, this is unsatisfactory when specifying non-deterministic processes. We, therefore, propose to extend LOTOS with a disjunction operator in order to achieve more implementation freedom while maintaining the possibility to describe non-deterministic processes. In contrast with similar proposals we maintain the operational semantics
