Queen's Gambit Declined: Semi-Tarrasch Defense, San Sebastian Variation
ECO D41
Move order
1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. cxd5 Nxd5 5. e4 Nxc3 6. bxc3 c5 7. Nf3 cxd4 8. cxd4 Bb4+ 9. Bd2 Qa5
Ideas
ECO D covers queen-pawn games and closed structures, including many Gambits and the Queen's Gambit complex. White builds a pawn center and keeps the position more closed than after 1. e4. This entry tracks a longer branch in the opening tree. Use the diagram and SAN list to recognize the tabiya, then try the line against Maia to explore typical plans in practice.