The ten annotation rules

Classical games only · 505,367 analyzed games · boards show the position before the move

	Rule	Conditions	Per game	Example
??	Blunder	EV* loss* ≥ 30 pp*	0.16	Tal – Smyslov, 1959 40...Rgd7?? Candidates 1959 (Bled/Zagreb/Belgrade)
?	Mistake	EV loss ≥ 13 pp	1.47	Karpov – Kasparov, 1987 50...R7f3? World Chess Championship 1987 (FIDE)
?!	Inaccuracy	EV loss ≥ 8.5 pp	1.52	Alekhine – Nimzowitsch, 1930 10...Qd7?! San Remo 1930
!!	Brilliant Sacrifice	best move SEE* ≥ 3 EV after ≥ 0.7 EV gain* ≥ 3 pp	0.11	Paulsen – Morphy, 1857 17...Qxf3!! New York 1857
!	Surprising Move	best move EV after ≥ 0.35 EV gain ≥ 2 pp surprising move	0.67	Short – Timman, 1991 33.Kf4! Tilburg 1991
	Hard Move	best move difficult position* EV after ≥ 0.35 EV gain ≥ 2 pp	0.47	Karpov – Unzicker, 1974 24.Ba7! Olympiad 1974 (Nice): Final A
	Sacrifice	best move SEE ≥ 2 EV after ≥ 0.35 EV gain ≥ 2 pp	0.34	Reti – Alekhine, 1925 26...Re3! Baden-Baden 1925
	Minor Sac	best move SEE ≥ 1 EV after ≥ 0.35 EV gain ≥ 2 pp surprising move*	0.28	Larsen – Spassky, 1970 10...Ng4! USSR vs Rest of World 1970
!?	Speculative Sac	not best SEE ≥ 1 EV loss < 5 pp vs. best contested position* surprising move	0.24	Nezhmetdinov – Chernikov, 1962 12.Qxf6!? Rostov 1962
!?	Sharpening Move	not best EV loss < 3 pp vs. best win and loss chance up ≥ 2 pp contested position	0.06	Larsen – Bobotsov, 1969 47.Nf7!? Palma 1969

*EV = expectation (see XPA)

*loss = negative change in expectation after move played

*pp = percentage point

*SEE = Static Exchange Evaluation, the net material the move leaves en prise, in pawns: 1 = pawn, 2 = exchange, 3 = minor piece

*gain = positive change in expectation after move played

*surprising move = policy gives less than 5% probability

*difficult position = expected loss ≥ 6 pp

*contested position = EV before between 0.3 and 0.7 with draw probability < 0.85

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