Page 18 - D. Raleigh "Knots and ropes for climbers"

The Figure-8 on a Bight is the best knot to
use when connecting a rope to an anchor.

Besides being the premier anchor knot, the Figure Eight on a Bight makes a passable middleman's knot
(clip to it with two carabiners having their gates opposed and reversed or, better, use locking
carabiners), although the Butterfly is better, being easier to untie after it has held a hard load.
Likewise, you can use the Figure Eight on a Bight to tie out a short section of rope that has been
damaged; just don't expect the knot to slide through any carabiners.

Tie the Figure Eight on a Bight near the end of a rope, and you can use it to clip a haul line to your
harness.

Common Uses
Anchoring rope to protection
Attaching middleman for glacier travel
Attaching haul line to harness