Encyclopaedia of Chess Openings

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 books are intended for an international audience and contain only a small amount of text, which is in several languages.

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.