#square_knot  a double knot made of two half hitches and used to join the ends of two cords
  supertype:  knot  any of various fastenings formed by looping and tying a rope (or cord) upon itself or to another rope or to another object
  subtype:  reef_knot__flat_knot  a square knot used in a reef line
     subtype:  granny_knot__granny  a reef knot crossed the wrong way and therefore insecure

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