ECO E49: Nimzo-Indian Defense

ECO E49 is part of volume E — Indian Defenses. The Lichess chess-openings dataset files one named line under it. It is Nimzo-Indian Defense: Normal Variation, Botvinnik System: 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 O-O 5. Bd3 d5 6. a3 Bxc3+ 7. bxc3.

That position has come up in 42,768 Lichess games between players rated 1600 to 2500: White won 52.2%, 5.6% were drawn and Black won 42.2%.