Opening books.

The openings of chess, with at least a minimum interest, are organized in what is known as the Encyclopaedia of openings, or more more frequently by his acronyms in English ECO.

The ECO contains 2.014 variations out of different openings, comprising a grand total of 20.697 moves. Many of those moves repeat from some variations to others and actually, the ECO contains only 4.037 different positions.

To download the ECO in PGN format, press here. The Viewer can read the downloaded file without uncompressing it.

The opening book, instead of registering the move sequences, tend to save the positions with a series of statistical data and evaluation.

At present there are four opening books available for the Viewer:

• ECO. Contains the full 4.037 ECO positions. Download here. Do not confuse this ECO book with the PGN file mentioned above. They are different files.
• 2500. This book contains the ECO positions, plus the opening positions that ocurred in games where both players had an elo equal or above 2500. The book contains the positions that appear at least 4 times in those games. Download here.

The opening book is used from the "Blackboard". First it has to be registered from the "Books" tab of the Viewer configuration options (button ).

To use a book please follow the following steps:

1. Download the book.
2. Uncompress it into any folder on your hard drive.
3. Register it by the configuration options.
4. Use the button opening ( ) from the Blackboard window.

To register an opening book you press the button located in the toolbar at the main window of the Viewer:

You need to select the tab "Bases" to get access to a set of options. There are two sections with the same data, the one upside is the corresponding to the opening books.

In ID field you should enter a short sentence describing the book and by the button ( ), you search for the file that resulted from uncompressing the downloaded file. You are then ready to press the Alta button.

To know if the board position is contained in the book, first select the book to be used from the dropdownlist as shown in the next image.

The above image shows the "Elite" book selected.

After you press the button ( ), if the current position is in the book, a new window opens up:

That shows:

• The number of games that arrived at this position.
• The ECO code of the opening.
• The average year of the games (arithmetic average of year in which each one of the games was played).
• The Success factor. This number tries to measure the strengh of the position from the results obtained in the games where it was played. A positive value means that the position should favour White. It is obtained adding the games won by White, subtracting the games lost, but giving more importance to the more recent games. For example, if the result is a positive number, with the number of won games lower to the number of lost games, it means that the victories are more recent than the defeats.

• The name and concrete variation.

If the squares Won, Lost and Draws appear blank, it means that it is a ECO position ECO that was not played in any of the games present in the current book.