There are exactly 209 positions of reciprocal zugzwang among rook and pawn versus rook endgames. Positions with zugzwang occur fairly often in chess endgames, especially in king and pawn endgames. Studying positions of reciprocal zugzwang is in the analysis of endgames. There are positions of mutual zugzwang in the endgame with two knights versus one pawn. Reciprocal zugzwang is possible, but very rare and usually seen in endgame compositions. White must defend accurately and utilize reciprocal zugzwang. In a position with reciprocal zugzwang, only the player to move is actually in zugzwang. Corresponding squares are squares of mutual zugzwang. Wolfgang Heidenfeld thus considers it a misnomer to call this a true zugzwang position. The diagram on the right shows a position of reciprocal zugzwang. Kf5 puts White in zugzwang and Black wins. The first diagram shows the simplest possible example of zugzwang. Gd1, a waiting move, and Black is in zugzwang. Opposition, and Black is in zugzwang. This gives the inferior side enough tempo moves to avoid zugzwang.