ENCYCLOPAEDIA OF CHESS OPENINGS
»ECO Code« is a trademark of Chess Informant Inc.

ECO
D0

ECO
D1

ECO
D2

ECO
D3

ECO
D4

1. d4 d5 2. c4 c6

1. d4 d5
2. c4 dc4

1. d4 d5 2. c4 e6

1. d4 d5 2. c4 e6
3. Nc3 Nf6 4. Nf3

without 2. c4

without 3. Nc3

4... c5

2. c4 without
2... c6, 2... dc4,
2... e6

3. Nc3 without
3... Nf6

4... c6

3... Nf6 without
4. Nf3, 4. Bg5

4. Nf3 without
4... c5, 4...c6

ECO
D5

ECO
D6

ECO
D7

ECO
D8

ECO
D9

1. d4 d5 2. c4 e6
3. Nc3 Nf6
4. Bg5 Be7

1. d4 Nf6
2. c4 g6
(with 3... d5)

1. d4 Nf6 2. c4 g6 3. Nc3 d5

1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. Nf3

without 4... Be7

5. e3 0-0
6. Nf3 Nbd7

without 3. Nc3

without 4. Nf3

4... Be7 without
5. e3

5. e3 without
5... 0-0

5... 0-0 without
6. Nf3

6. Nf3 without
6... Nbd7