This article uses algebraic notation to describe chess moves. A chess opening theory table or ECO (Encyclopedia of Chess Openings) table presents lines of moves, typically (but not always) from the starting position. Notated chess moves are presented in the table from left to right. Variations on a given line are given horizontally below the parent line. Theory tables are a way of representing chess variations from a position in a quick reference manner. Chess opening books sometimes make extensive use of them to represent a good amount of information in a compact form. Here on Wikibooks the compactness is not so useful, but the quick reference manner can help the chess player familiar with theory tables quickly locate the information required. Chess opening theory tables are commonly published in opening books with annotations by experienced chess players. These tables are typically arranged in a compact manner to allow experienced players to see variations from a position quickly. Usually, the table indicates that either White or Black has equal, slightly better, or better chances at the end of the variation. Sometimes, this information is distilled down to mere symbols or the percentage of games (usually tournament games) where White won – no information is usually given on what the assessment is based on or how to proceed in the game. Typically, each table has a heading indicating the moves required to reach the position for which the table provides an analysis. The first row provides the move numbers with subsequent row representing different variations. White half-moves are shown above black half-moves. Ellipses (...) represent moves that, for the variation, are identical to the variation above. Bold type indicates that another variation is considered elsewhere – usually in another table. A dash (-) indicates that the variation transposes to a variation elsewhere. Transpositions are common in chess – a given position can often be reached by different move orders – even move orders with more or fewer moves. It is common to add notes regarding whether a certain variation is considered better for White or for Black. This is done at the end (i.e. to the right) of every variation, using shorthand notation regarding specific positions. For instance, the remark += (or +/=) indicates that White has a slight advantage. If reversed (=+ or =/+) this would be true for Black instead. 1. d4 Nf6 2. c4 e5 1.e4 Nf6 Chess opening theory books that provide these tables are usually quite large and difficult for beginners to use. Because the table entries typically do not include the themes or goals involved in a given line, beginners will either try to memorize the tables (not an easy task) or simply drown in the detail. Chess Opening Theory aims to bridge this gap by providing this type of information at the end of each line. Sicilian Defence, Najdorf Variation English Attack 1. e4 c5 2. Nxd4 Nf6 5. Nc3 a6 6. Be3 e5 7. Nb3 Be6 8. f3 1. e4 c5 2. Nxd4 Nf6 5. Nc3 a6 6. Be3 e6 7. f3 The Classical Main Line 1. e4 c5 2. Nxd4 Nf6 5. Nc3 a6 6. Bg5 e6 7. f4 Qb6 1. e4 c5 2. Nxd4 Nf6 5. Nc3 a6 6. Bg5 e6 7. f4 Be7 Classical Variation 1. e4 c5 2. Nxd4 Nf6 5. Nc3 a6 6. Be2 e5 7. Nb3 Be7 8. O-O O-O 1. e4 c5 2. Nxd4 Nf6 5. Nc3 a6 6. Be2 e6 7. O-O Other sixth moves for White 1. e4 c5 2. Nxd4 Nf6 5. Nc3 a6 6. f4 Fischer–Sozin Attack 1. e4 c5 2. Nxd4 Nf6 5. Nc3 a6 6. Bc4 e6 7. Bb3 1. e4 c5 2. Nxd4 Nf6 5. Nc3 a6 6. Bc4 e6 7. Bb3 Richter–Rauzer Attac 1. e4 c5 2. Nxd4 Nf6 5. Nc3 Nc6 6. Bg5 e6 7. Qd2 a6 8. O-O-O Bd7 1. e4 c5 2. Nxd4 Nf6 5. Nc3 Nc6 6. Bg5 e6 7. Qd2 a6 8. O-O-O h6 1. e4 c5 2. Nxd4 Nf6 5. Nc3 Nc6 6. Bc4 e6 7. Be3 1. e4 c5 2. Nxd4 Nf6 5. Nc3 Nc6 6. Be2 1. e4 c5 2. Nxd4 Nf6 5. Nc3 g6 6. Be3 Bg7 7. f3 O-O 8. Qd2 Nc6 1. e4 c5 2. Nxd4 Nf6 5. Nc3 g6 6. Be3 Bg7 7. f3 Nc6 8. Qd2 O-O 1. e4 c5 2. Nxd4 Nf6 5. Nc3 e6 6. Be2 a6 7. O-O 1. e4 c5 2. Nxd4 Nf6 5. Nc3 e6 6. g4 1. e4 c5 2. Qxd4 1. e4 c5 2. Nf3 d6 3. Bb5+ Bd7 4. Bxd7+ Qxd7 1. e4 c5 2. Nf3 d6 3. Bb5+ Nc6 4. O-O Bd7 1. e4 c5 2. Nf3 d6 3. Bb5+ Nd7 1. e4 c5 2. Nf3 d6 3. c3 Nf6 1. e4 c5 2. Nf3 d6 3. Nc3 1. e4 c5 2. Nxd4 Nf6 5. Nc3 e5 6. Ndb5 d6 7. Bg5 a6 8. Na3 b5 1. e4 c5 2. Nxd4 Nf6 5. Nc3 e6 6. Ndb5 1. e4 c5 2. Nxd4 e6 5. Nc3 Qc7 6. Be3 a6 1. e4 c5 2. Nxd4 e6 5. Nc3 Qc7 6. Be2 a6 7. O-O Nf6 8. Be3 1. e4 c5 2. Nxd4 e6 5. Nc3 Nf6 6. Ndb5 1. e4 c5 2. Nxd4 e6 5. Nc3 a6 1. e4 c5 2. Nxd4 e6 5. Nc3 d6 1. e4 c5 2. Nxd4 e6 5. Nb5 d6 1. e4 c5 2. Nxd4 g6 5. Nc3 Bg7 6. Be3 Nf6 7. Bc4 O-O 8. Bb3 1. e4 c5 2. Nxd4 e5 5. Nb5 d6 1. e4 c5 2. Nxd4 Qc7 1. e4 c5 2. Nf3 Nc6 3. Bb5 g6 4. O-O Bg7 1. e4 c5 2. Nf3 Nc6 3. Bb5 e6 1. e4 c5 2. Nxd4 a6 5. Bd3 Bc5 6. Nb3 Be7 1. e4 c5 2. Nxd4 a6 5. Bd3 Nf6 6. O-O 1. e4 c5 2. Nxd4 a6 5. Nc3 Qc7 6. Bd3 1. e4 c5 2. Nxd4 a6 5. Nc3 Nc6 1. e4 c5 2. Nxd4 a6 5. Nc3 b5 1. e4 c5 2. Nf3 e6 3. Nc3 a6 1. e4 c5 2. Nf3 e6 3. d3 Nc6 4. g3 1. e4 c5 2. Nf3 e6 3. c3 1. e4 c5 2. Nf3 g6 3. d4 1. e4 c5 2. Nf3 a6 Nunn's Chess Openings. 1999. 1999. Aleksandar Matanovic, editor, Encyclopaedia of Chess Openings, 5 volumes (Belgrade: Šahovski informator)
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