London System, with Bd3
ECO A48
Move order
1. d4 Nf6 2. Nf3 g6 3. Bf4 Bg7 4. e3 d6 5. Bd3
Ideas
ECO A covers irregular and flank openings—systems that skip the main e4/d4 fight early. 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.