From eight chain thru formation: All do a Half Square Thru. Centers now turn to face partner and finish the Square Thru as per call (usually given as "Centers go one, two or three more hands"). If the centers go two more hands, finishes in lines facing out. If they go one or three more hands, finishes in one of the varieties of T-Bone formation.
Jack Lasry 1970
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.