2. Solution approaches by application area and criticality

The notion of the "criticality" of an application, also referred to as the level of "risk" it represents, is a two-dimensional quantity. It is based on the product of the probability of occurrence of the feared event and the resulting level of severity (on a scale of 1 to 10, for example) should the event occur. The notion of severity is in turn defined by a two-dimensional quantity qualifying: on the one hand, the overall level of safety, i.e. maintaining the integrity of goods and people; on the other hand, the level of availability, i.e. total or partial continuity of nominal service. The classification of fields of application by "criticality" given in table 1 is a way of addressing the major families of solutions improving the operating reliability of the systems concerned.