Power rail and lines
The power rail on the left represents the TRUE value and initiates the rung state. Any object connected to this rail is always powered.
Horizontal lines always represent a data flow from the left to the right.
If a vertical line has several items connected on the left, then it represents an OR operation.
You can insert a segment of horizontal line at any location in order to freely draw flow lines. The "vertical line" button enables you to set or remove (toggle) a segment of vertical line on the right of the selected cell.