Bristol clearance

A Bristol clearance uses two same-color pieces that travel at long range along horizontal rows, vertical columns, or diagonals. The first piece moves along a line and passes beyond a critical square. This clears the line so that a second piece with matching line movement can later reach or pass through that square.

The visual idea is one piece moving ahead through a corridor so another can follow. Order matters: the leading piece does not merely step sideways out of the way. It uses the very line needed by the following piece. The maneuver may support an attack, a defense, an obstruction, or whatever goal the composition specifies.

The pieces need not be identical. A rook and a queen, for example, both move along rows and columns and can form a Bristol on one of those lines. What matters is that both can use the chosen line and that the first journey performs the clearance.