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ECO Codes

ECO stands for Encyclopedia of Chess Openings. They are codes identifying chess opening, each consisting of a letter from A to E, followed by two digits. For example - C33 represents the King's Gambit Accepted. There are five hundred distinct ECO codes.

To see a game's ECO code, select Game-> Identify Opening and examine the Game Information window.

Scid Extensions to ECO

The ECO system is however fairly limited, and insufficient for modern games. Some codes are never used, while others are overly frequent. To improve this, Scid allows an optional extension to the basic ECO codes. Codes may be extended with a letter from a to z, with a further extension - a digit from 1 to 4 - being possible but not yet used. So an extended code may look like A41e or E99b2. Many of the codes common in modern master-level games have extensions defined in the Scid ECO file.

The ECO Browser Window

Scid's ECO Browser shows positions associated with each ECO code, and their frequency and performance amongst ECO classified games in the current database.

The upper pane shows a bar graph with three sections: the lowest (light blue) represents White wins, the middle represents draws, and the top (dark blue), the number of Black wins. The graph illustrates at a glance an openings characteristics - whether draws are common or White or Black is winning. To go to a deeper ECO level click on a bar in the graph, or to go higher right-click, press the button, or left-arrow.

You can also navigate with keys, writing the ECO code you are interesting in. For instance, if you want to see the ECO code B75 (for the Yugoslav Attack in the Sicilian Dragon), you just press the key combination 'b75' (or 'B75'). If you want to go up to a more general code, like B7, you can just press Left-Arrow.

The bottom pane shows the positions for a particular ECO code according to the ECO file loaded.

The ECO classify games button will permanently add ECO classifications to selected games in the current database.

Loading an ECO File

Scid will attempt to load the default scid.eco at start up. If it cannot, or you wish to use another file, one may be loaded manually via the Load ECO File feature, after which this will be loaded automatically.

ECO Code System

The basic structure of the ECO system is:

A 1.d4 Nf6 2...; 1.d4 ...; 1.c4; 1.various

B 1.e4 c5; 1.e4 c6; 1.e4 d6; 1.e4 various

C 1.e4 e5; 1.e4 e6

D 1.d4 d5; 1.d4 Nf6 2.c4 g6 with 3...d5

E 1.d4 Nf6 2.c4 e6; 1.d4 Nf6 2.c4 g6