This video is a technical explanation of how the internal mechanics of the If-Then node works.
This video demonstrate how to set up the logic to use the If Then node so that system A (connected to the IF and THEN inputs) can override system B (connected to the ELSE input). e.g. When system A has a long or short output, it will always show system A on the chart. But, when system A is neutral (zero outputs), that is when system B will show on the chart. In this example system A identifies an overbought/oversold condition, and system B identifies a trending condition.