About this opening
Modern Defense: Semi-Averbakh Variation, Pterodactyl Variation Accepted is an opening in the Encyclopedia of Chess Openings,
classified under code A04. ECO group A (A00–A99)
covers flank and irregular openings, including the English, Bird, Réti and Dutch defences. This particular variation is reached
after 10 half-moves from the
starting position, with the move sequence 1. Nf3 g6 2. d4 Bg7 3. e4 d6 4. c4 c5 5. dxc5 Qa5+.
It belongs to the Modern Defense family. Within that family this is a level-2 branch (the Semi-Averbakh Variation → Pterodactyl Variation Accepted line).
The opening sequence in prose form: 1.Nf3 g6, 2.d4 Bg7, 3.e4 d6, 4.c4 c5, 5.dxc5 Qa5+. From this position the encyclopaedia records no further canonical continuations — practical play branches into unnamed transpositions or returns to the parent line for alternative ideas.
Use the interactive board above to walk through the moves position-by-position. Click any move in the navigation to step backwards, or use the keyboard arrow keys. For statistical data — how often master-level players have reached this position, White's win-rate, draw frequency, Black's score — see the panel in the right column.
Caissly's coverage of A04 extends through every named sub-variation in this line and across all four locales (English, Spanish, Portuguese, Russian). Where editorial commentary exists for a specific variation it appears as the page body; otherwise the page presents the structural data, board, and statistics as shown here.