ECO E21
4 named openings and variations are classified as E21. ECO (Encyclopaedia of Chess Openings) codes group openings from A00 to E99 by their opening moves.
- Nimzo-Indian Defense: Three Knights VariationE211. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Nf3
- Nimzo-Indian Defense: Three Knights Variation, Euwe VariationE211. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Nf3 c5 5. d5 Ne4
- Nimzo-Indian Defense: Three Knights Variation, Korchnoi VariationE211. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Nf3 c5 5. d5
- Nimzo-Indian Defense: Three Knights Variation, Shocron GambitE211. d4 Nf6 2. c4 e6 3. Nf3 Bb4+ 4. Nc3 c5 5. d5 b5