ON THIS WIKI
The Anchor Sentinel is used together with a World Anchor to alter the chunk loading abilities of the world anchor. The Anchor Sentinel is paired with the World Anchor with a Crowbar, the World Anchor will then only load the chunks in a straight line from the anchor to the sentinel. It is possible to load up to a total of 9 chunks in a straight line in this way.
Your sentinel is where you start the pairing, where you will get the message "Anchor sentinel pairing was initiated." After you use your crowbar on the world anchor of your choice, you will get the message "World anchor was successfully paired," and the work is done. Note however, that the same messages display if you then attempt to pair a second anchor sentinel with the same world anchor, but doing so will change the pairing; you cannot add additional sentinels to the same anchor.