This complicated version of the Surgeon’s knot is a strong multipurpose bend. The Academic knot is very secure, even on lines of different size, and it is easier to untie, than the Reef knot, which tends to jam. The Academic knot is extensively used in surgery and in climbing.
Cross the running ends, putting the left one over the right one.
Pass both running ends around the standing parts downward, making an overhand knot.
Pass the running ends around the standing parts again, but upward.
Cross the running ends again, placing the end of the right rope on top.
Pass both running ends around the standing parts upward.
Tighten the knot.
The Academic knot is complete.