1. A computer implemented method for instantiating a process in a process modelling system, the method comprising: using a processor, modelling the process as a process model comprising process objects, the process objects comprising a plurality of passive process objects and a plurality of active process objects including a plurality of users categorized in a plurality of different roles associated with the process; using the processor, automatically transforming the process model into a meta model comprising the process objects of the process model as definitions of process object types in said meta model, wherein the transformation of the process model into the meta model includes creating a definition of a distinct process object type for each individual users categorized in the same role associated with the process, such that the meta model enables individual assignment of individual users categorized in the same role to the same or different process object types.