ECO E25: Nimzo-Indian Defense

ECO E25 is part of volume E — Indian Defenses. The Lichess chess-openings dataset files 3 named lines under it. The shortest is Nimzo-Indian Defense: Sämisch Variation: 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. f3 d5 5. a3 Bxc3+ 6. bxc3 c5 7. cxd5.

That position has come up in 42,970 Lichess games between players rated 1600 to 2500: White won 50.6%, 6.6% were drawn and Black won 42.8%.