All ECO Codes
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D40
D40
Queen's Gambit
Declined, Semi-Tarrasch, Symmetrical Variation
1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Nf3 c5 5.e3 Nc6 6.Bd3 Bd6 7.O-O O-O