Modelling describes, using a suitable formalism, what the design is. Modelling may be formal and mathematical in nature, or may be presented by means of techniques such as state machine diagrams. Modelling activities can provide increased understanding of and confidence in the design. Animation means the exploration of design behaviour under certain conditions. Such animation may be done symbolically, or on actual inputs to the system.
Animation is useful for checking the appropriateness of the design.
It also helps to increase understanding of the design. Formal verification will require formal statements of both the model of the design and the critical requirement. Although it can be difficult to carry out, formal design verification can be a very effective way of providing assurance of safety or security, as well as discovering design flaws. DOVE makes use of a graphical user interface for Isabelle , called XIsabelle . The version used in DOVE has been modified somewhat.