The loops of multiple-loop controls should be distinctly marked to prevent the selection or use of the wrong loop.
Additional Information:
A multiple-loop controller is a digital controller that can control multiple variables via independent channels, one per control loop. Each channel acts as a separate control device. For example, a single controller may be capable of controlling 10 different variables, each on a separate control loop. Operators access these loops through the user interface of the controller device. However, because there may be few cues to identify the loops, operators may fail to correctly recognize the loop accessed and may control the wrong variable.