steps.Unified Process, IBM and Rational’s version – altogether called Rational Unified Process (RUP) form the process which was developed and refined during the nineties and which today may be seen as reference model for all modern software developing processes. The process is described in the book “The Unified Software Development Process” by ‘The Three Amigos’ Grady Booch, James Rumbaugh and Ivar Jacobson (Addison-Wesley, 1999). The process was defined in addition to the three men’s efforts with developing UML.