This might be described as the Reef Knot for springy or slippery synthetics as it performs the same task but is more secure in modern materials. There are two forms; the more established is formed in the same way as a Reef Knot but with a second turn at each stage. Thus the square knot becomes a rectangle as shown in the diagram above left.
The second form (above right) has two initial overhand knots again, but instead of a second pair on top there is just one. Then, when the knot is drawn up tight the upper overhand knot forms a parallel crossover leaving the ends sticking out on opposite sides. When drawn up tightly it forms a very secure, locked knot. The photographs show the differences.
