ECO chess openings classification

ECO stands for the “Encyclopaedia of Chess Openings” and is used by almost all chess players and publications all over the world. Individual openings variations have a code consisting of a letter (A – E) and a two-digit number.

There are also names for most of them.

Examples:

A51 Budapest Gambit, Fajarowicz Variation

B72 Sicilian Dragon: 6 Be3, lines with h3+Bc4 and sidelines

The ECO classification used by this program was improved by leading openings expert GM Dr. John Nunn.

The program can create an openings key based on the ECO code.

ECO Codes

When you save a game, the correct ECO code is automatically inserted.

1.	Volume C covers the French Defense and all double King pawn openings

2.	Volume B covers all 1.e4 openings in which Black replies with something other than 1.e6 or 1.e5.

Volume D contains all of the double Queen pawn openings and all openings in which 3.Nc7 Bg7 doesn't follow the opening moves 1.d4 Nf6 2.c4 g6 (that's what the parentheses mean in the list above: that those moves are not played -- so, in other words, it's the 1.d4 Nf6 2.c4 openings in which 2...g6 is played, but 3.Nc3 Bg7 doesn't follow).

4.	Volume E has the openings in which either 2...e6 or 2...g6 3.Nc3 Bg7 follow 1.d4 Nf6 2.c4.

5.	Volume A contains everything that doesn't fall into the categories of the other four volumes (stuff like the English and the various flank openings).