Having a post which is perfectly smooth is a good selling point but its not ideal when you have to add a anchoring ropes.
Therefore we have specially hardened steel pins in our progromm which are called securing pins.
Thrue the pre-punch holes in the posts these pins can be inserted and on top you can install the anchoring ropes,
This is how to prevent the ropes from sliden down, the same way this securing bolt is used for our anti sink plate.