Page 60 - Nate Fitch, Ron Funderburke "Climbing Knots"

The BHK is tied by turning a single bight of rope into a
double bight.

Then an overhand on a bight is tied with two strands of
material, creating a redundant knot.

The resulting loop can be managed by clipping back
into the master point.
Using the Rope for Anchoring 47