In order to understand the new standard it is important to realize that it has two fundamentally different user types: 1.) the designer of safety related sub-systems, and 2.) the designers of safety related systems. In general the sub-system designer (a component manufacturer, such as Curtis Instruments) will need to provide the required data for the system designer to ensure that it is of adequate integrity for the system (the vehicle). This will usually require some testing, analysis, and calculation. The resulting data will be expressed in the format required by the standard as follows:
MTTFd
Mean Time to Dangerous Failure
CCF
Common Cause Failures
The system designer (the vehicle manufacturer) will then use this data to perform some relatively straightforward calculations to determine the overall Performance Level (PL) of the system.