What does the "L" stand for?

[Chimo]

Working on my first build, a "MOAR", and wondering if someone could clue me in to what the "L" between the ground and LED spots stands for?

Any help is appreciated.

[cooder]

That is the pad where you connect the wire going to the foot switch that is switching the LED.
Check out the footswitch wiring essentials here:
https://www.madbeanpedals.com/tutorials/index.html