Creates an anchor from the given plane's center which can be used to track a spot in the real world over time. Anchors automatically adjust their position to attempt to stay fixed to a point detected in the real world, this allows you to place an object there without it drifting too much. Returns an ID you can use to reference this anchor later. The plane result does not need to exist after creating an anchor from it, you can safely call ARGetPlanesFinish afterwards. The anchor will persist and use some tracking resources until you specifically delete it with ARDeleteAnchor or you destroy the AR session.
integer ARCreateAnchorFromPlane( index )