Chess ++ Symbol: Mate or Double Check

Explanation

The symbol ++ has no universal meaning. In the notation appendix of the International Chess Federation (FIDE), it may represent checkmate, the situation in which the king is attacked and has no legal reply, as an alternative to .

Many books and websites instead use ++ for double check, a position in which two pieces attack the king at the same time. Two sources can therefore display the same mark with different meanings.

Standard Algebraic Notation (SAN) is the strict move-writing system used by , a plain-text format for storing games. SAN uses for any check and # for mate; it has no special mark for double check.

Common confusions

Checkmate

FIDE permits ++ for mate on a scoresheet, but game files intended for software use # as the standard form.

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Double check

Some publications use ++ for two simultaneous attacks on the king, although standard notation writes only +.

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Sources

1.Appendix C. Algebraic Notation, FIDE Rules Commission
2.Standard: Portable Game Notation Specification and Implementation Guide, rec.games.chess contributors; coordinated by Steven J. Edwards
3.Chess annotation symbols, Wikimedia Foundation

Explanation

Common confusions

Sources

Related terms