What is the usage of the four pins on a control?

origami

There are 4 pins where the arrow points to. I dont know what is the usage of the pins. I can find related tutorial.

So what is the usage of the pins?
And where can I find the related official manual?

TwistedTwigleg

It’s the anchors of the Control node, which defines how and where the Control node will resize when the game window resizes. This page on the documentation has some information on ui anchors.