The systematic top-down design of mixed-signal systems requires an abstract specification of the intended functions. However, hybrid systems are systems whose parts are specified using different time models. Specifications of hybrid systems are not purely functional as they also contain structural information. The structural information is introduced by partitioning the specification into blocks with a homogeneous time model. This often leads to inefficient implementations. In order to overcome this problem, a homogeneous representation for behavior of hybrid systems -- KIR -- is introduced. This representation makes it possible to represent behavior in all time models in a common way so that the separation in different modeling styles is no longer necessary. Rules for re-writing the KIR-graph are given which permit the description of the same behavior in another time model.