ECO D91: Grünfeld Defense

ECO D91 is part of volume D — Closed & Semi-Closed Games. The Lichess chess-openings dataset files one named line under it. It is Grünfeld Defense: Three Knights Variation, Petrosian System: 1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. Nf3 Bg7 5. Bg5.

That position has come up in 750,786 Lichess games between players rated 1600 to 2500: White won 48.1%, 6.1% were drawn and Black won 45.9%.