Page 63 - Nate Fitch, Ron Funderburke "Climbing Knots"

Doubled Cordellette with Load-
Limiting Overhand Knots: The Quad
When load-limiting overhand knots are tied into a
doubled-over cordellette or extra-long sling, the result
is also a redundant, self-adjusting, and strong anchor-
ing system. Unlike a sling, the load-limiting overhand
knots tied into the quad are composed of four strands
of cordellette. The bulkier overhand knot is usually
easier to untie after sustained cyclical loads.

A doubled-over cordellette or long sling with knots
can configure the quad. By clipping three of the
four master point strands, a failure of one anchor
point will not result in total failure.
50 CLIMBING: KNOTS