How and when does AddUserAnchorFromGameObject assign an anchor to a Game Object?

Hi,

I'm going through the UnityARUserAnchorExample.cs script, and I don't see that you're assigning an anchor to any position.
In UnityARUserAnchorComponent.cs, you're obtaining the anchor ID using the AddUserAnchorFromGameObject method, but how is the anchor assigned to a position in real space? Is that position dynamically changing, assigning the anchor to a different place in the real world?

Confused. Thanks.