/spl mu/-Charts are a way of specifying reactive systems, i.e. systems which are in some environment to which they have to react, based on the well-established formalism Statecharts. This paper gives (very abbreviated) examples of translating /spl mu/-charts to Z, which is itself a well-established language for specifying computational systems with tried and tested methods and support tools which guide its effective use in systems development. We undertake this translation in order that investigation of the modelled system can be performed before expensive and lengthy implementation is considered. We also present an extension of the /spl mu/-charts and the related Z to deal with a simple command language, local variables and integer-valued signals.