From Pathfinder Wiki
Use: The Strangle knot is a simple binding knot. Similar to the constrictor knot, it also features an overhand knot under a riding turn. The difference is that the ends emerge at the outside edges, rather than between the turns as for a constrictor. This knot is actually a rearranged double overhand knot and makes up each half of the double fisherman's knot. When tightened, it is very slip-resistant. It is ideal for constructing a pilot ladder (like a rope ladder, but with wooden rungs).