Rockwell Automation Logix5000 Controllers Ladder Diagram Programming Manual - Manual (Page 10)

Chapter 1 Program ladder diagram
There is no limit to the number of parallel branch levels that you can enter. This
example shows a parallel branch with five levels. The main rung is the first branch
level, followed by four additional branches.
You can nest branches to as many as 6 levels. This example shows a nested branch.
The bottom output instruction is on a nested branch that is three levels deep.
Large rungs with complex, nested branches result in having to scroll through the
ladder editor and may end up spanning multiple pages when you print the logic.
To make it easier to maintain, divide the logic into multiple smaller rungs.
10 Rockwell Automation Publication 1756-PM008E-EN-P - October 2014