An imaginary system in which the ultimately controlled variable and the specified command have the relationship which was stipulated.
Figure 2 - Block diagram of automatic control system (5-2-045) incorporating a closed loop (5-2-080)
Note:: It is a basis for performance standards.
Reference: ANSI (modified)
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM