ECO Codes

These days, you will often find a short 3 digit alpha-numeric code, printed alongside many published chess games. These codes are known as "ECO" codes, and they are a way of classifying the opening moves of a chess game.

Some chess players will be familiar with ECO classification and may even be able to identify their own particular favourite opening lines, such as a "B90" or a "C74". However, more often than not, these codes will be over-looked, as being little more than cryptic id keys, useful only to modern chess computer databases.

The ECO classification system originates from a 5 volume book (now also a database) that was first published by the Serbian company, Šahovski informator (Chess Informant). in 1966. This encylopoedic work is compiled by notable chess players, and it aims to categorise the opening moves of hundreds of thousands of master games.

'Informator' is designed to bridge language barriers and so it contains very limited amounts of text (shown in in eight languages). The bulk of the books contains diagrams of positions and chess moves that are shown in International figurine algebraic notation. Rather than using language, special symbols are used to comment the moves ('Chess Punctuation'). The moves are then provided in a table format that concisely presents the best opening lines.

To further bridge language barriers, traditional opening names are not used. The original five volumes of 'Informator' were categorised from, "A" to "E", and each book focused on broadly different catagories of opening. Generally, Volume 'A' dealt with 'Flank' openings, 'B' dealt with 'Semi-Open' lines, 'C' with 'Open' lines, 'D' with 'Closed'lines and 'E' with 'Indian' openings. However, as this work was originally being produced in a printed format, some adjustments were needed eded, to accomodate the publisher's printing requirements and effectively 'balance' the 5 volumes. This is why, some openings, such as the French Defence, may appear to be mis-categorised.

In the western speaking world, this notable work become known as the 'Encylopoedia of Chess Openings' or 'ECO' for short. Popular publications and moden chess database systems have since adopted this coding system and use of ECO classification is now widedspread.

For reference, a more detailed ECO Classification is given below.

'A' - Flank Openings
ECO Opening
A00 Irreg. (incl. Grob; Polish [Solosky])
A01 Nimzovich-Larsen attack
A02 Bird (incl.From gambit)
A03 Bird's Opening : Lasker variation
A04 Reti
A05 Reti : King's Indian attack
A06 Reti : Old Indian attack
A07 Reti : King's Indian attack
A08 Reti : King's Indian attack
A09 Reti : Advance variation & Keres var
A10-A39 English Opening
A40 Queen's pawn
A41 Old Indian defence
A42 Modern Robatsch
A43 Old Benoni : Franco-Benoni defence
A44 Old Benoni defence
A45 Trompowsky & d4 Irreg.
A46 Queen's pawn game
A47 Queen's Indian defence
A48 King's Indian : East Indian defence
A49 King's Indian : Fianchetto without c4
A50 Queen's pawn game
A51 Budapest Defence
A52 Budapest defence
A53-A55 Old Indian defence
A56 Benoni defence
A57-A59 Benko gambit
A60-A79 Benoni defence
A80-A99 Dutch
'B' - 'Semi-Open' games (Other than the French Defence)
ECO Opening
B00 King's Pawn irreg. (incl Nimzowitch Def)
B01 Scandinavian gambit (incl Centre Counter)
B02-B05 Alekhine's defence
B06 Robatsch (Modern) defence
B07-B09 Pirc
B10-B19 Caro-Kann defence
B20 Sicilian Defence (wing)
B21 Grand Pix / Smith Morra
B22 Alapin
B23-B26 Closed
B27-B288 O'Kelly variation
B29-B31 Nimzovich-Rubinstein variation
B32 Labourdonnais-Loewenthal (Kalashnikov)
B33 Pelikan (Lasker/Sveshnikov) variation
B34-B39 Accelerated Fianchetto
B40 Anderssen variation
B41-B43 Kan variation
B44 Sicilian, Szen, hedgehog variation
B45-B49 Taimanov variation
B50 wing gambit deferred
B51 Canal-Sokolsky
B52 Canal-Sokolsky attack, 3...Bd7
B53 Sicilian, Chekhover variation
B54-B55 Prins variation, Venice attack
B56 Venice attack
B57 Sozin, not Scheveningen
B58-B59 Boleslavsky variation
B60-B69 Richter-Rauzer
B70-B79 Dragon variation
B80-B85 Scheveningen variation
B86-B89 Sozin attack
B90-B99 Najdorf
'C' - 'Open' games (and the French Defence)
ECO Opening
C01 French : Exchange variation
C02 French : Advance variation
C03-C09 French : Tarrasch
C10 French : Rubinstein variation
C11 French : Burn variation
C12 French : MacCutcheon variation
C13 French : Albin-Alekhine-Chatard attack
C14 French : Classical variation
C15-C19 French : Winawer (Nimzovich) variation
C20 Alapin's Opening
C21 Centre game (Danish Gambit)
C22 Centre game
C23-C24 Bishop's Opening
C25-C29 Vienna Game/Vienna Gambit
C30 King's Gambit Declined
C31-C32 KGD (Falkbeer)
C34 KGA King's knight's gambit
C35 KGA : Cunningham defence
C36 KGA : Abbazia defence
C37 KGA Muzio Lolli Variations
C38 KGA : Greco gambit
C39 KGA : Allgaier gambit, kieseritsky
C40 Others incl Damiano, Latvian
C41 Philidor
C42-C43 Petrov
C44 Ponziani, Scotch
C45 Scotch game
C46 Three knights game
C47-C49 Four knights
C50-C55 Giuoco Piano (incl Evans)
C56-C59 Two Knights Defence
C60 Cozio
C61 Bird's Defence
C62 Ruy Lopez : Old Steinitz defence
C63 Ruy Lopez : Schliemann defence
C64 Ruy Lopez : Classical (Cordel) defence
C65 Ruy Lopez : Berlin defence
C66 Ruy Lopez : Closed Berlin defence
C67 Berlin Def
C68-C69 Ruy Lopez : Exchange variation
C70 Ruy Lopez : Alapin's defence deferred
C71-C76 Ruy Lopez : Modern Steinitz defence
C77 Ruy Lopez : Morphy defence
C78 Ruy Lopez : Archangelsk
C79 Ruy Lopez : Steinitz defence deferred
C80 Ruy Lopez : Open (Tarrasch) defence
C81 Ruy Lopez : Open, Howell attack
C82 Ruy Lopez : Open, Dilworth variation
C83 Ruy Lopez : Open, 9...Be7, 10.Re1
C84 Ruy Lopez : Closed defence
C85 Ruy Lopez : Exchange doubly deferred
C86 Ruy Lopez : Worrall attack
C87 Ruy Lopez : Closed, Averbach variation
C88 Ruy Lopez : Closed
C89 Ruy Lopez : Marshall counter-attack
C90-C99 Ruy Lopez : Closed
'D' - 'Closed' games and 'Semi-Closed' games (incl. the Grünfeld Defence)
ECO Opening
D00 Q Pawn, Blackmar gambit
D01 Richter-Veresov attack
D02 Queen's pawn game
D03 Torre attack
D04 Queen's pawn game
D05 Colle system
D07 QGD : Chigorin defence
D08 QGD : Albin counter-gambit
D09 QGD : Albin counter-gambit, 5.g3
D10-D19 QGD Slav
D20-D25 Queen's gambit accepted
D26-D29 QGA : Classical variation
D30-D31 QGD : Slav & semi Slav
D32-D34 QGD : Tarrasch defence
D35-D36 QGD : Exchange variation
D37-D39 QGD : Ragozin variation
D40-D42 QGD : Semi-Tarrasch defence
D43-D49 QGD Semi-Slav (Incl Meran)
D50 QGD : Canal (Venice) variation
D51 QGD : Alekhine variation
D52 QGD : Cambridge Springs defence
D53 QGD : Lasker variation
D54 QGD : Anti-neo-Orthodox variation
D55 QGD : Neo-Orthodox variation
D56-D57 QGD : Lasker defence
D58-D59 QGD : Tartakower variation
D60-D69 QGD : Orthodox defence
D70-D99 Neo-Gruenfeld defence
'E' - Indian Defences (Other than the Grünfeld Defence)
ECO Opening
E00 Neo-Indian (Seirawan) Attack
E00 Catalan Opening
E01 Catalan : Closed
E02 Catalan : Open, 5.Qa4
E03 Catalan : Open, Alekhine Variation
E03 Catalan : Open, 5.Qa4 Nbd7, 6.Qxc4
E04 Catalan : Open, 5.Nf3
E05 Catalan : Open, Classical Line
E06 Catalan : Closed, 5.Nf3
E07 Catalan : Closed, 6...Nbd7
E07 Catalan : Closed, Botvinnik Variation
E08 Catalan : Closed, 7.Qc2
E08 Catalan : Closed, Zagoryansky Variation
E08 Catalan : Closed, Qc2 & B3
E08 Catalan : Closed, Spassky Gambit
E09 Catalan : Closed, Main Line
E09 Catalan : Closed, Sokolsky Variation
E10 Queen's Pawn Game
E10 Blumenfeld Counter-Gambit
E10 Blumenfeld Counter-Gambit Accepted
E10 Blumenfeld Counter-Gambit, Dus-Chotimursky Variation
E10 Blumenfeld Counter-Gambit, Spielmann Variation
E10 Dzindzikhashvili Defence
E10 Doery Defence
E11 Bogo-Indian Defence
E11 Bogo-Indian Defence, Gruenfeld Variation
E11 Bogo-Indian Defence, Nimzovich Variation
E12 Queen's Indian Defence
E12 Queen's Indian : Miles Variation
E12 Queen's Indian : Petrosian System
E12 Queen's Indian : 4.Nc3
E12 Queen's Indian : 4.Nc3, Botvinnik Variation
E13 Queen's Indian : 4.Nc3, Main Line
E14 Queen's Indian : 4.E3
E14 Queen's Indian : Averbakh Variation
E15 Queen's Indian : 4.G3
E15 Queen's Indian : Nimzovich Variation (Exaggerated Fianchetto)
E15 Queen's Indian : 4.G3 Bb7
E15 Queen's Indian : Rubinstein Variation
E15 Queen's Indian : Buerger Variation
E16 Queen's Indian : Capablanca Variation
E16 Queen's Indian : Yates Variation
E16 Queen's Indian : Riumin Variation
E17 Queen's Indian : 5.Bg2 Be7
E17 Queen's Indian : Anti-Queen's Indian System
E17 Queen's Indian : Opovcensky Variation
E17 Queen's Indian : Old Main Line, 6.O-O
E17 Queen's Indian : Euwe Variation
E18 Queen's Indian : Old Main Line, 7.Nc3
E19 Queen's Indian : Old Main Line, 9.Qxc3
E20 Nimzo-Indian Defence
E20 Nimzo-Indian : Kmoch Variation
E20 Nimzo-Indian : Mikenas Attack
E20 Nimzo-Indian : Romanishin-Kasparov (Steiner) System
E21 Nimzo-Indian : Three Knights Variation
E22 Nimzo-Indian : Spielmann Variation
E23 Nimzo-Indian : Spielmann, 4...C5, 5.Dc Nc6
E23 Nimzo-Indian : Spielmann, Karlsbad Variation
E23 Nimzo-Indian : Spielmann, San Remo Variation
E23 Nimzo-Indian : Spielmann, Staahlberg Variation
E24 Nimzo-Indian : Saemisch, Botvinnik Variation
E25 Nimzo-Indian : Saemisch Variation
E26 Nimzo-Indian : Saemisch, O'Kelly Variation
E27 Nimzo-Indian : Saemisch Variation
E28 Nimzo-Indian : Saemisch Variation
E29 Nimzo-Indian : Saemisch, Main Line
E29 Nimzo-Indian : Saemisch, Capablanca Variation
E30 Nimzo-Indian : Leningrad Variation
E31 Nimzo-Indian : Leningrad, Main Line
E32 Nimzo-Indian : Classical Variation
E33 Nimzo-Indian : Classical, Milner-Barry (Zurich) Variation
E34 Nimzo-Indian : Classical, Noa Variation
E35 Nimzo-Indian : Classical, Noa Variation, 5.Cd Ed
E36 Nimzo-Indian : Classical, Botvinnik Variation
E36 Nimzo-Indian : Classical, Noa Variation, Main Line
E37 Nimzo-Indian : Classical, Noa Variation, Main Line, 7.Qc2
E37 Nimzo-Indian : Classical, San Remo Variation
E38 Nimzo-Indian : Classical, 4...C5
E39 Nimzo-Indian : Classical, Pirc Variation
E40 Nimzo-Indian : 4.E3
E41 Nimzo-Indian : E3, Huebner Variation
E42 Nimzo-Indian : 4.E3 C5, 5.Ne2 (Rubinstein)
E43 Nimzo-Indian : Fischer Variation
E44 Nimzo-Indian : Fischer Variation, 5.Ne2
E45 Nimzo-Indian : 4.E3, Bronstein (Byrne) Variation
E46 Nimzo-Indian : 4.E3 O-O
E46 Nimzo-Indian : Reshevsky Variation
E47 Nimzo-Indian : 4.E3 O-O, 5.Bd3
E48 Nimzo-Indian : 4.E3 O-O, 5.Bd3 D5
E49 Nimzo-Indian : 4.E3, Botvinnik System
E50 Nimzo-Indian : 4.E3 E8G8, 5.Nf3, Without ...D5
E51 Nimzo-Indian : 4.E3, Ragozin Variation
E52 Nimzo-Indian : 4.E3, Main Line With ...B6
E53 Nimzo-Indian : 4.E3, Main Line With ...C5
E53 Nimzo-Indian : 4.E3, Keres Variation
E53 Nimzo-Indian : 4.E3, Gligoric System With 7...Nbd7
E54 Nimzo-Indian : 4.E3, Gligoric System, Smyslov Variation
E55 Nimzo-Indian : 4.E3, Gligoric System, Bronstein Variation
E56 Nimzo-Indian : 4.E3, Main Line With 7...Nc6
E57 Nimzo-Indian : 4.E3, Main Line With 8...Dc And 9...Cd
E58 Nimzo-Indian : 4.E3, Main Line With 8...Bxc3
E59 Nimzo-Indian : 4.E3, Main Line
E60 King's Indian Defence
E60 King's Indian : Anti-Gruenfeld
E60 King's Indian : Danube Gambit
E60 King's Indian : 3.G3, Counterthrust Variation
E61 King's Indian Defence, 3.Nc3
E61 King's Indian : Smyslov System
E62 King's Indian : Fianchetto Variation
E62 King's Indian : Fianchetto, Larsen System
E62 King's Indian : Fianchetto, Kavalek (Bronstein) Variation
E62 King's Indian : Fianchetto, Simagin Variation
E63 King's Indian : Fianchetto, Panno Variation
E64 King's Indian : Fianchetto, Yugoslav System
E65 King's Indian : Fianchetto, Yugoslav, 7.O-O
E66 King's Indian : Fianchetto, Yugoslav Panno
E67 King's Indian : Fianchetto, Classical Variation
E68 King's Indian : Fianchetto, Classical Variation, 8.E4
E69 King's Indian : Fianchetto, Classical Main Line
E70 King's Indian : Kramer System
E70 King's Indian : Accelerated Averbakh System
E71 King's Indian : Makagonov System (5.H3)
E72 King's Indian With E4 & G3
E72 King's Indian : Pomar System
E73 King's Indian : 5.Be2
E73 King's Indian : Semi-Averbakh System
E73 King's Indian : Averbakh System
E74 King's Indian : Averbakh, 6...C5
E75 King's Indian : Averbakh, Main Line
E76 King's Indian : Four Pawns Attack
E77 King's Indian : Four Pawns Attack
E77 King's Indian : Four Pawns Attack, Florentine Gambit
E78 King's Indian : Four Pawns Attack, With Be2 And Nf3
E79 King's Indian : Four Pawns Attack, Main Line
E80 King's Indian : Saemisch Variation
E81 King's Indian : Saemisch, 5...O-O
E81 King's Indian : Saemisch, Byrne Variation
E82 King's Indian : Saemisch, Double Fianchetto Variation
E83 King's Indian : Saemisch, 6...Nc6
E83 King's Indian : Saemisch, Ruban Variation
E83 King's Indian : Saemisch, Panno Formation
E84 King's Indian : Saemisch, Panno Main Line
E85 King's Indian : Saemisch, Orthodox Variation
E86 King's Indian : Saemisch, Orthodox, 7.Nge2 C6
E87 King's Indian : Saemisch, Orthodox, 7.D5
E87 King's Indian : Saemisch, Orthodox, Bronstein Variation
E88 King's Indian : Saemisch, Orthodox, 7.D5 C6
E89 King's Indian : Saemisch, Orthodox Main Line
E90 King's Indian : 5.Nf3
E90 King's Indian : Larsen Variation
E90 King's Indian : Zinnowitz Variation
E91 King's Indian : 6.Be2
E91 King's Indian : Kazakh Variation
E92 King's Indian : Classical Variation
E92 King's Indian : Andersson Variation
E92 King's Indian : Gligoric-Taimanov System
E92 King's Indian : Petrosian System
E92 King's Indian : Petrosian System, Stein Variation
E93 King's Indian : Petrosian System, Main Line
E94 King's Indian : Orthodox Variation
E94 King's Indian : Orthodox, Donner Variation
E94 King's Indian : Orthodox, 7...Nbd7
E95 King's Indian : Orthodox, 7...Nbd7, 8.Re1
E96 King's Indian : Orthodox, 7...Nbd7, Main Line
E97 King's Indian : Orthodox, Aronin-Taimanov Variation (Yugoslav Attack / Mar Del Plata Variation)
E97 King's Indian : Orthodox, Aronin-Taimanov, Bayonet Attack
E98 King's Indian : Orthodox, Aronin-Taimanov, 9.Ne1
E99 King's Indian