ECO E31: Nimzo-Indian Defense

ECO E31 is part of volume E — Indian Defenses. The Lichess chess-openings dataset files one named line under it. It is Nimzo-Indian Defense: Leningrad Variation, Benoni Defense: 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Bg5 h6 5. Bh4 c5 6. d5 d6.

That position has come up in 7,652 Lichess games between players rated 1600 to 2500: White won 46.9%, 4.8% were drawn and Black won 48.2%.