ECO E27: Nimzo-Indian Defense

ECO E27 is part of volume E — Indian Defenses. The Lichess chess-openings dataset files one named line under it. It is Nimzo-Indian Defense: Sämisch Variation: 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. a3 Bxc3+ 5. bxc3 O-O.

That position has come up in 289,937 Lichess games between players rated 1600 to 2500: White won 48.2%, 4.8% were drawn and Black won 47.0%.