The halyard is spliced onto a short piece of thicker line and that engages in a cleat at the top of the mast. There's then a boss on the side of the mast that you route the halyard around to another cleat on the front of the mast. If you get it tight it does not flap that I've ever noticed. The remaining tail then tucks into a sail pocket by the tack. All rather neat and simpler than I'm making it sound.My main experience with this sort of thing are OK's and Finns- we used halyard locks up top. Is that Aero practice?