Queen's Gambit Declined: Semi-Tarrasch Defense, Main Line

The Queen's Gambit Declined: Semi-Tarrasch Defense, Main Line is a chess opening classified under ECO code D42 in the Closed & Semi-Closed Games family, arising from 1.d4 d5, including the Queen's Gambit, Slav Defense, and related systems. It is reached after 7 moves: 1. d4 Nf6 2. c4 e6 3. Nf3 d5 4. Nc3 c5 5. cxd5 Nxd5 6. e3 Nc6 7. Bd3. The resulting position leaves black to move.