IDCM (Incremental Development of Conforming Models) is a JAVA tool providing a set of conformance relations allowing behavioural model releases to be compared. It includes a translator allowing UML state machines to be transformed into LTS (labelled transition systems). Behavioural model releases may evolve by a refinement process through two axes : an horizontal axe allowing a new functionnality to be specified (extension conformance relation) ; vertical axe allowing specification to be detailed and undeterminism to be reduced (reduction conformance relation). Whatever the strategy of refinement may be, the model obtained at the end of the refinement process conforms the initial specification (implementation conformance relation).