ECO E50: Nimzo-Indian Defense

ECO E50 is part of volume E — Indian Defenses. The Lichess chess-openings dataset files one named line under it. It is Nimzo-Indian Defense: 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 O-O 5. Nf3.

That position has come up in 237,521 Lichess games between players rated 1600 to 2500: White won 46.8%, 5.3% were drawn and Black won 47.9%.