WeBotLib and LED / AxonII wiring question

[Kelpy]

Probably another dumb question, but here goes.
I'm using the excellent WebBotLib Project Designer for a project, which uses some LED's on my AxonII.
The designer assigns 2 pins to an led, A0 signal and A0 live+.
I'm confused, as I expected a connection to the ground pin as well.
Does this mean when I use software to activate the led, the signal pin becomes a ground pin, and the circuit is completed?

[Webbot]

Yep thats correct. When the signal pin goes low it is 0v ie ground. So the current flows from the +ve through the LED+resistor to the signal pin.

[Kelpy]

Thank you, once again, Webbot. Wanted to be sure before going live