ECO volume D: Closed and semi-closed games

ECO D22

3 named openings and variations are classified as D22. ECO (Encyclopaedia of Chess Openings) codes group openings from A00 to E99 by their opening moves.

Queen's Gambit Accepted: Alekhine DefenseD221. d4 d5 2. c4 dxc4 3. Nf3 a6
Queen's Gambit Accepted: Alekhine Defense, Alatortsev VariationD221. d4 d5 2. c4 dxc4 3. Nf3 a6 4. e3 Bg4 5. Bxc4 e6 6. d5
Queen's Gambit Accepted: Alekhine Defense, Haberditz VariationD221. d4 d5 2. c4 dxc4 3. Nf3 a6 4. e3 b5