“…Examples of such situations are: (i) the addition of a new component to the system (e.g., a new switch is added to a telecommunications network or a new sensor is added to a manufacturing system); (ii) the replacement of an old component by a new component with di!erent capabilities (Agre, Clare, Lee, Brandin, Hoskins & Perrone, 1995); (iii) the addition of a new speci"cation on the legal behavior of the controlled system that requires`re"ninga the system model (i.e., modeling the behavior with greater detail using additional events); and (iv) changes in the system functionality or`process changesa, e.g., a new part is added to the set of parts that a manufacturing system can process (as in a programmable or recon"gurable factory (National Research Council, 1995)) or a new feature is added to a telecommunications system (see Cameron, Gri!eth, Lin, Nilson, Schnure & Velthuijsen, 1993;Thistle, MalhameH , Hoang & Lafortune, 1997;Chen, Lafortune & Lin, 1997).…”