ECO A39: English Opening

ECO A39 is part of volume A — Flank Openings. The Lichess chess-openings dataset files one named line under it. It is English Opening: Symmetrical Variation, Mecking Variation: 1. c4 Nf6 2. Nf3 c5 3. Nc3 Nc6 4. g3 g6 5. Bg2 Bg7 6. O-O O-O 7. d4.

That position has come up in 334,144 Lichess games between players rated 1600 to 2500: White won 53.0%, 8.0% were drawn and Black won 39.0%.