This is a list of chess openings, organize by the Encyclopaedia of Chess Openings (ECO) code. In 1966, Chess Informant categorized the chess openings into five broad areas ("A" through "E"), with each of those broken down into one hundred subcategories ("00" through "99"). The openings were published in five volumes of Encyclopaedia of Chess Openings, with volumes labeled "A" through "E". This is a list of chess openings by the ECO classification.