ECO A90
3 named openings and variations are classified as A90. ECO (Encyclopaedia of Chess Openings) codes group openings from A00 to E99 by their opening moves.
- Dutch Defense: Nimzo-Dutch VariationA901. d4 f5 2. c4 Nf6 3. g3 e6 4. Bg2 Bb4+
- Dutch Defense: Nimzo-Dutch Variation, Alekhine VariationA901. d4 f5 2. c4 Nf6 3. g3 e6 4. Bg2 Bb4+ 5. Bd2 Be7
- Dutch Defense: Stonewall Variation, Modern VariationA901. d4 f5 2. c4 e6 3. Nf3 Nf6 4. g3 c6 5. Bg2 d5 6. O-O Bd6