| symbolic representation of the actions in a system by functional blocks, summing points and branching points linked by action lines
SEE: Figures 1 and 2.
Note 1 to entry: The action lines do not necessarily represent physical connections, like electrical wires.
Note 2 to entry: Functional blocks, action lines, summing points, and branching points are elements of the functional diagram.
Note 3 to entry: This entry was numbered 351-23-01 in IEC 60050-351:2006.
Figure 1 – Functional diagram indicating typical elements of an elementary open-loop control system
Figure 2 – Functional diagram indicating typical elements of an elementary closed-loop control system