A chess opening theory table or ''ECO'' table (''

Encyclopaedia of Chess Openings The ''Encyclopaedia of Chess Openings'' () is a reference work describing the state of opening theory in chess, originally published in five volumes from 1974 to 1979 by the Serbian company Šahovski Informator (Chess Informant). It is curre ...

'') presents lines of moves, typically (but not always) from the starting position. Notated

chess Chess is a board game for two players, called White and Black, each controlling an army of chess pieces in their color, with the objective to checkmate the opponent's king. It is sometimes called international chess or Western chess to dist ...

moves are presented in the table from left to right. Variations on a given line are given horizontally below the parent line.

Arrangement

Chess opening A chess opening or simply an opening is the initial stage of a chess game. It usually consists of established theory; the other phases are the middlegame and the endgame. Many opening sequences have standard names such as the "Sicilian Defen ...

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. Often, this information is distilled down to mere

symbols A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise very different co ...

(" Σ" for example) 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.

Shortcomings

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 or simply drown in the detail. The Wikibook ''Chess Opening Theory'' aims to bridge this gap by providing this type of information at the end of each line.

Notation

Typically, each table has a heading indicating the moves required to reach the position for which the table provides an analysis. The example below is for the opening position, so no moves are shown in the heading. The first row provides the move numbers with subsequent rows representing different variations. Since the initial position is not always the opening position, these numbers will not always start at "1." 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

hyphen The hyphen is a punctuation mark used to join words and to separate syllables of a single word. The use of hyphens is called hyphenation. ''Son-in-law'' is an example of a hyphenated word. The hyphen is sometimes confused with dashes ( figure ...

(-) or

en dash The dash is a punctuation mark consisting of a long horizontal line. It is similar in appearance to the hyphen but is longer and sometimes higher from the baseline. The most common versions are the endash , generally longer than the hyphen b ...

(–) 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. The table may also provide percentage of games won by white for each variation, based on the results of the games considered in creating the table.

Development

Chess openings are studied in great depth by serious players. "

Novelties A novelty item or simply novelty is an object which is specifically designed to serve no practical purpose, and is sold for its uniqueness, humor, or simply as something new (hence " novelty", or newness). The term also applies to practical items w ...

", or new, previously unexplored variations are often discovered and played by professional players. These new lines can refute lines that were previously thought to be sound. The games that represent this discovery process are represented in these ever-changing and expanding tables. With the advent of computer databases, even the most casual player can explore an opening line deeply, looking for novelties to spring on their opponents.

Example

External sources of chess opening theory tables

John Nunn John Denis Martin Nunn (born 25 April 1955) is an English chess grandmaster, a three-time world champion in chess problem solving, a chess writer and publisher, and a mathematician. He is one of England's strongest chess players and was forme ...

(Editor), Graham Burgess, John Emms, Joe Gallagher (1999), ''Nunn's Chess Openings''. . *

Nick de Firmian Nicholas Ernest de Firmian (born July 26, 1957) is an American chess player who received the FIDE title of Grandmaster (GM) in 1985. He is a three-time U.S. chess champion, winning in 1987 (with Joel Benjamin), 1995, and 1998. He also tied for ...

, Walter Korn (1999), ''

Modern Chess Openings ''Modern Chess Openings'' (usually called ) is a reference book on chess openings, first published in 1911 by the British players Richard Clewin Griffith (1872–1955) and John Herbert White (1880–1920). The fifteenth edition was published in ...

: MCO-14''. . *

Aleksandar Matanović Aleksandar Matanović (born May 23, 1930) is a Serbian chess grandmaster. Following the death of Yuri Averbakh at the age of 100 on May 7, 2022, Matanović became the oldest living grandmaster. Chess career Awarded the GM title in 1955, Matano ...

, editor,

, 5 volumes (Belgrade: Šahovski informator) {{Chess *Chess opening theory table