In the context of an effort to answer the OMG RFP for Modeling and Analysis of Real-Time Embedded systems (MARTE), we are defining extensions to the simple time model of UML2. After a brief review of some time-related UML profiles, we focus on the specificity of our approach: the ability to take account of multiform time-a concept inherited from reactive system modeling. Using an example from the automotive industry, we illustrate the use of our profile to represent, to constraint and to analyze behaviors depending on multiform time.