← All chapters Chapter 04

Functions and Systems

Confuse what a system is with what it does, and the tree inherits the confusion.

A clean separation of function and system is a matter of result quality, not vocabulary. The chapter distinguishes logical from technical interface descriptions, settles who owns which specification between customer and supplier, and carries the same split into the functional and technical safety concepts. The malfunction, owned by the customer, is what the fault tree takes as its top level event.