It forms the first part of the surgeon's knot and both sides of a double fisherman's knot. According to The Ashley Book of Knots, "A double overhand knot tied in a cat-o'-nine-tails is termed a blood knot."
This knot is a crucial component of surgical procedures and forms part of both the surgeon's knot and the double fisherman's knot. It is also known as a "blood knot" when tied in a cat-o'-nine-tails fashion.