Each domain has its own interpretation of time. We propose to extend UML, which is more and more used in the domain of real-time embedded applications, with a concept of time inherited from reactive system modeling : multiform time. After a brief review of some UML profiles, we present our extensions and we illustrate on an example from the automotive industry how to represent and to constraint behaviors depending on multiform time. We advocate that this model of time offers wider possibilities than restricting models only to the physical time.