Functional structure is often the starting point and typically a structure to
describe a system in a plant/facility, for example a system/sub system and with
physical serial objects (pumps, valves, tanks etc.) on the lowest level. It’s
used in order to organize equipment from a plants functional aspect, for
example, where equipment is a functional part of systems like: Production Line,
Drilling, Feed Water System, Instrument Air System and Waste Water System.