10. Step 7: Maintenance

10.1 Process

The aim of this seventh stage is to keep the software system in a state of use that will enable it to continue to be used long after it has been installed. This is the notion of maintenance in operational conditions (MCO). In fact, over time, events occur which have a more or less serious impact on operations. These events fall into three categories (see table 1 ):

• malfunctions ;

• functional or technical developments;

• other intervening events.