Page 86 - Peter Randall "The Craft of the Knot.."

If you are making scaffolding or other large square frames, Square
Lashing is the method to use on the corners that meet at right angles.

STEP 1 Arrange two poles at a 90-degree angle to each other. Anchor
one end with a Clove Hitch (see Chapter 8) and start wraps, as shown.

STEP 2 Make four wraps, passing over the pole at the top, and under

the pole at the bottom, keeping each wrap tight.

STEP 3 Make two frapping turns, staying in front of the back pole and
behind the front pole, just as you would do with a Sheer Lashing.