ECO Volume A: Flank Openings

100 ECO codes, 817 named lines. Linked names have their own family guide on this site; unlinked names are listed for reference only.

What sets this volume apart

Volume A’s headline character is the flank openings: first moves (c4, Nf3, g3, b3, b4, and more) that delay any central pawn advance in favor of piece pressure and fianchettoes from the side, staking a claim on the center from a diagonal rather than occupying it outright. But the volume’s own numeric range grew to be a genuine catch-all too: several d4-based systems that don’t fit neatly under Volumes B through E - Black defenses like the Benoni, Dutch Defense, Benko Gambit, and Old Indian Defense, plus White’s own Trompowsky Attack - are also classified here, a real quirk of how the ECO system’s A-codes were assigned rather than a strategic thread running through every family in the volume.

All codes in Volume A

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Other volumes

Volume B · Volume C · Volume D · Volume E · All ECO families →