ECO A21
5 named openings and variations are classified as A21. ECO (Encyclopaedia of Chess Openings) codes group openings from A00 to E99 by their opening moves.
- English Opening: King's English Variation, Keres DefenseA211. c4 e5 2. Nc3 d6 3. g3 c6
- English Opening: King's English Variation, Kramnik-Shirov CounterattackA211. c4 e5 2. Nc3 Bb4
- English Opening: King's English Variation, Reversed SicilianA211. c4 e5 2. Nc3
- English Opening: King's English Variation, Smyslov DefenseA211. c4 e5 2. Nc3 d6 3. Nf3 Bg4
- English Opening: King's English Variation, Troger DefenseA211. c4 e5 2. Nc3 Nc6 3. g3 d6 4. Bg2 Be6