Undeveloped Event
An undeveloped event is used when further resolution of the event is not necessary for proper evaluation of the fault tree or when the information necessary for developing the event is not currently available. While an undeveloped event is similar to a basic event, it is represented by a different symbol to signify that it is possible to break this event down into associated gates and events, even though this has not been done for this particular analysis.
Example
A vehicle will not start if it has no fuel OR if it has some other mechanical problem. Thus, an OR gate is inserted in the tree along with a basic event, No Gas, and an undeveloped event, Mech Problem. The undeveloped event indicates that other mechanical problems are not within the scope of the analysis.
