Both
ECO and
Chess Informant are published by the
Belgrade-based company
Šahovski Informator. The moves are taken from thousands of master games and from published analysis in
Informant and compiled by the editors, most of whom are
grandmasters, who select the lines which they consider most relevant or critical. The chief editor since the first edition has been
Aleksandar Matanović (1930-2023). The openings are provided in an
ECO table that concisely presents the opening lines considered most critical by the editors.
ECO covers the openings in more detail than rival single volume publications such as
Modern Chess Openings and ''
Nunn's Chess Openings'', but in less detail than specialized opening books. The books are intended for an international audience and contain only a small amount of text, which is in several languages. The bulk of the content consists of diagrams of positions and chess moves, annotated with
symbols, many of them developed by Chess Informant.
Chess Informant pioneered the use of
Figurine Algebraic Notation to avoid the use of initials for the names of the pieces, which vary between languages. Instead of the traditional names for the openings,
ECO has developed a coding system that has also been adopted by other
chess publications. There are five main categories, "A" to "E", corresponding to the five volumes of the earlier editions, each of which is further subdivided into 100 subcategories, for a total of 500 codes. The term "
ECO" is often used as a shorthand for this coding system.
ECO code is a registered trademark of
Chess Informant. ==Openings covered==