ECO Volume A · A00–A99
Volume A — Flank & Uncommon Openings
Everything that starts away from the classical centre: the English, Réti, Bird's, plus the Benoni, Benko, Dutch and other fighting defences to 1.d4. 1.c4, 1.Nf3, 1.f4 & the sharp d4 defences.
English Opening
A10The English Opening is the thinking player's 1.c4 — an opening of patience and geometry. Instead of fighting for the centre with pawns, White builds a flexible bind and strikes later, exactly where Black is weakest. It transposes into reversed Sicilians, Catalan structures and hedgehogs, making it a lifetime repertoire in one move.
English Opening
A101.c4 is chess in a dinner jacket: long-term plans, flexible structures and queenside space-grabbing, beloved by Botvinnik, Kasparov and Carlsen.
English Opening: Reversed Sicilian
A201...e5 turns the game into a Sicilian with colours reversed — White is a tempo up in the attacker's dream position.
Flank Opening Deep Lines: English, ...Nf6 Setup
A10The Anglo-Indian: the most popular English defence.
Indian Game
A50The gateway to the Indian defences: after 1.d4 Nf6 2.c4 Black chooses Nimzo, Budapest, Bogo, Old Indian and more.
Queen's Pawn Game
A40The catch-all for 1.d4 lines without an early c4 — including the Englund Gambit 1.d4 e5!? and Black's many offbeat setups.
Benoni Defence
A56The Modern Benoni: Black accepts a cramped position and fights back with the g6-bishop, piece pressure and queenside play.
Benoni Defence, Modern Variation
A60The Modern Benoni main move order: maximum tension, the g7 bishop, and the fight over e4 and d5.
Benoni, Classical with Nf3
A70The Classical Benoni: pure piece play — Bd3/Re1 plans versus ...c5-c4 and ...b5 queenside explosions.
English Opening, Anglo-Indian Defence
A15The Anglo-Indian (1.c4 Nf6) heads for King's-Indian and Réti-style battles where move orders decide who gets the structure they want.
English Opening, King's English
A201...e5 turns the game into a reversed Sicilian — the same attacking patterns with White a tempo up.
English Opening: Hedgehog System
A30Black's spiky a6-b6-d6-e6 constellation waits like a hedgehog: cute until you touch it.
English Opening: Keres Variation
A23The main-line King's English: immediate queenside expansion against the reversed-Dragon structure.
English Opening: Mikenas-Carls Variation
A18The sharpest English line: 3.e4 grabs the centre and forces immediate structural decisions.
English Opening: Symmetrical Main Line
A39The theoretical heart of the Symmetrical English — sharp piece play around d5 and the dark squares.
English Opening: Symmetrical Variation
A30Black mirrors everything, reaching double-fianchetto structures where the first concrete mistake decides.
English, Closed System
A25The Closed English: a slow squeeze with f4, h3 and Be3 pressure against Black's compact kingside.
English, Mikenas-Carls Variation
A18The sharpest English line: 3.e4 grabs the centre and forces immediate structural decisions.
English, Symmetrical Variation
A301...c5 mirrors White's setup — Hedgehog structures, Botvinnik systems and maneuvering duels where every tempo counts.
English, Symmetrical, Main Line
A38The main-line Symmetrical: full development first, then the decisive d4/...d5 central clashes.
English, Symmetrical, Main Line with d4
A39The theoretical heart of the Symmetrical English — sharp piece play around d5 and the dark squares.
Flank Opening Deep Lines
A10The deep-line archive of Volume A: named sub-variations of the English, Réti, Bird's, Dutch, Benoni and Benko — the lines that decide real games once both players know the first ten moves.
Flank Opening Deep Lines: Benoni, Classical Setup
A65The classical setup: the Modern Benoni's main structure.
Flank Opening Deep Lines: Benoni, Modern ...g6 Setup
A65The g6 setup: the Modern Benoni's fianchetto structure.
Flank Opening Deep Lines: English, ...c5 Setup
A30The Symmetrical: the mirror defence to 1.c4.
Flank Opening Deep Lines: English, ...e5 Setup
A20The King's English: the reversed-Sicilian defence.
Flank Opening Deep Lines: English, King's English 4.d44.g3 Setup
A28The g3 fianchetto setup: the King's English's main treatment.
Flank Opening Deep Lines: English, Symmetrical Hedgehog
A30The Hedgehog core: the a6-b6-d6-e6 chain versus the c4/d4 clamp.
Flank Opening Deep Lines: Réti Setup
A04The pure Réti: the most flexible first move in chess.
Flank Opening Deep Lines: Réti, ...Nf6 Setup
A05The ...Nf6 setup: the most popular Réti defence.
Modern Benoni
A56The Modern Benoni is the sharpest reply to 1.d4: Black accepts a cramped, locked structure and fights back with the g7-bishop, piece pressure and queenside play. Tal, Kasparov and every romantic since have used it to turn White's space into overextension.
Modern Benoni: Classical Variation
A70The classical main tabiya: piece pressure and timing battles around e4 and b5.
Réti Opening
A04Richard Réti's hypermodern masterpiece: instead of occupying the centre, White attacks it with pieces from the flanks. The bishop on g2 stares at d5 while pawns wait — then strikes exactly when Black overextends.
Réti Opening
A04The hypermodern masterpiece: White attacks the centre with pieces from a distance, leading to rich manoeuvring battles.
Réti Opening, 1...Nf6
A05With 1...Nf6 Black keeps maximum flexibility — the game can become a Queen's Indian, Catalan or pure Réti.
Benko Gambit
A57The Benko (Volga) Gambit is the purest example of positional compensation in chess: Black trades a pawn — often two — for permanent pressure down the a- and b-files and a monster bishop on g7. The compensation never fades; it just changes form.
Benko Gambit
A57Black trades a pawn — often two — for permanent a/b-file pressure and the monster g7 bishop: compensation made visible.
Benko Gambit Accepted
A58The full Benko structure: open files, dark-square strategy and endings where Black's pieces outfight White's pawns.
Benko Gambit, 7.e4 Main Line
A59The classical main line: White grabs the centre, Black's bishop stares down the long diagonal — sharp and principled.
Benko Gambit: 5.e3 Setup
A57The immediate acceptance — the cleanest theory path into Benko structures.
Benko Gambit: Benko Accepted
A58The full Benko structure: open files, dark-square strategy and endgames where pieces outfight pawns.
Benko Gambit: King's Walk Line
A59The king retreats to g1 — White's best try to tuck the monarch away from the long diagonal.
Benko Gambit: Main Line 7.e4
A59The classical main line: White grabs the centre, Black's bishop stares down the diagonal.
Benoni, 6.e4
A65The classical Benoni formation: White takes the big centre, Black strikes back with ...g6/...Bg7 and ...Re8.
Benoni, Classical without 9.O-O
A72White's flexible 9.h3 setup keeps Re1 and Nd2 options open against Black's queenside counterplay.
Benoni, Classical, 10...a6
A74Black's ...a6/...b5 expansion meets White's a4 clamp — the structural Cold War of the Classical Benoni.
Benoni, Classical, 8.Bg5
A71The early Bg5 pin targets e7 pressure and g4 tricks — a sharp sideline with real venom.
Benoni, Classical, 9...Re8
A76The ...Re8/...Nbd7 setup readies ...b5 breaks — the most principled classical battleground.
Benoni, Classical, 9.O-O
A73The main Classical tabiya: Nd2-c4-e3 manoeuvres against ...b5/...a6 timing battles.
Benoni, Fianchetto System
A61White's fianchetto answers Black's — a slower Benoni where the dark-square battle replaces the pawn storms.
Benoni, Fianchetto with 8...O-O
A62The smooth Fianchetto Benoni: Black's ...Re8 and ...a6/...b5 queenside play against White's central clamp.
Benoni, Four Pawns Attack
A68White's maximalist centre: four pawns and an e5 break against Black's piece pressure and timing counters.
Benoni, Four Pawns, Main Line
A69The tactical resolution of the Four Pawns: knights dance on the dark squares while the centre burns.
Benoni, Pawn Storm
A66The e4-f4 wedge sets up g4-g5 pawn storms — brutal attacking chess on both wings.
Benoni, Taimanov Variation
A67Taimanov's Bb5+ check and e5 break — one of the sharpest, most analyzed Benoni battlegrounds.
Budapest Gambit
A51The Budapest Gambit is the classic club weapon against 1.d4: an immediate pawn sacrifice for open lines, quick development and a web of traps. Black gets real activity for real risk — and famous smothered-mate finishes when White yawns.
Budapest Gambit
A51Black's enterprising pawn sac rips open lines and sets instant traps — the classic club weapon against 1.d4.
Budapest Gambit, Rubinstein Variation
A52Rubinstein's refined main line: Black regains the pawn with piece activity and keeps the initiative brewing.
Budapest Gambit: Adler Variation
A51The solid knight-development answer — heading for the Rubinstein structures.
Budapest Gambit: Budapest ...Bb4+ Lines
A52The full regrouping: the knight recaptures with tempo and Black's pieces hum.