Chess opening · ECO A04
Colle System: Rhamphorhynchus Variation
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1. Nf3 c5 2. e3 g6 3. d4 Bg7 4. dxc5 Qa5+
Colle System: Rhamphorhynchus Variation is catalogued under ECO code A04. It is reached after 4 moves (8 half-moves): 1. Nf3 c5 2. e3 g6 3. d4 Bg7 4. dxc5 Qa5+. After the last move it is White to play. White opens 1. Nf3. It is a named variation of the Colle System, which has 3 catalogued lines in total.