Overlapping White Squares

It marks a pair of bishops in chess commentary. A bishop is the chess piece that moves diagonally; the pair means both remain in play for one side. Chess Informant, a Serbian chess magazine, used a compact chess-notation system to annotate expert games across language barriers. A multilingual encyclopedia of chess endings published in 1993 records this sign in that tradition. Chess Informant had been an important route for spreading chess expertise since the 1960s, including across the Iron Curtain.