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I. Introduction
What are the ECO Codes of the chess openings?.. All chess openings are divided into the 3 main types by the first moves:
• Open Games chess openings: 1.e4 e5
• Semi-Open Games chess openings: 1.e4 other than e5
• Closed Games chess openings: 1.other than e4 other than e5.
For chess beginners, this chess opening division by the combination of the first moves is simple and understandable. But chess professionals use another approach in chess opening classification -- They use the ECO Codes. As chess beginner you should know them in general, and it is advisable for you to know the ECO Codes of the main chess openings (for example: If you learn and make a collection of the Sicilian Defense chess opening games, you must select ECO codes B20-B99 from the downloaded PGN files).
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II. ECO Codes: A, B, C, D, E
When you open an ECO Codes book, you may find something like A18, D34, E70, E95, C67, and the combination of the first moves...
This is a different Classification of chess openings and their variations. Let's go deeper into the ECO Codes classification to learn more about chess openings...
ECO stands for Encyclopedia of Chess Openings. By the ECO classification, all chess openings and their variations are divided into 5 main types A, B, C, D, E by the combination of the first moves:
• A
Includes all chess openings, which:
- first moves are: without 1.d4, 1.e4
- first moves are: 1.d4 without 1... Nf6, 1... d5
- first moves are: 1.d4 Nf6 without 2.c4
- first moves are: 1.d4 Nf6 2.c4 without 2... e6, 2... g6
• B
Includes all chess openings, which:
- first moves are: 1.e4 without 1... c5, 1... e6, 1... e5
- first moves are: 1.e4 c5
Note: Separated, Sicilian Defense (1.e4 c5) is ECO Code B.
• C
Includes all chess openings, which:
- first moves are: 1.e4 e6
- first moves are: 1.e4 e5
Note: All Open Games chess openings (1.e4 e5) are ECO Code C.
• D
Includes all chess openings, which:
- first moves are: 1.d4 d5
- first moves are: 1.d4 Nf6 2.c4 g6 with 3... d5
• E
Includes all chess openings, which:
- first moves are: 1.d4 Nf6 2.c4 e6
- first moves are: 1.d4 Nf6 2.c4 g6 without 3... d5
III. ECO Codes: Number Subdivision 00-99
ECO Codes classification does not include any Names of chess openings and their variations: Just the letters, numbers, and the first moves... Each ECO type A, B, C, D, E is broken down into 100 subcategories, from 00 to 99. For example, let's see these ECO Code lines:
• C 23
1.e4 e5 2.Bc4
- without 2... Nf6
• C 24
1.e4 e5 2.Bc4 Nf6
You know that the designated move order of Bishop's Opening is 1.e4 e5 2.Bc4. See the above ECO Code lines and compare. You see now that the ECO Codes of Bishop's Opening are C23-C24. If you have downloaded the Bishop-opening-sample.pgn file and PGN Viewer Program in Lesson 16: Download PGN Viewer Program, you already know that the main variations of Bishop's Opening are:
• Berlin Defense: 1.e4 e5 2.Bc4 Nf6; ECO Code C24.
• Classical Defense (Boi Variation): 1.e4 e5 2.Bc4 Bc5; ECO Code C23.
• Philidor Counterattack: 1.e4 e5 2. Bc4 c6; ECO Code C23.
• The Nc6 Variation: 1. e4 e5 2. Bc4 Nc6; ECO Code C23.
• The d6 Variation: 1. e4 e5 2. Bc4 d6; ECO Code C23.
• Calabrian (Calabrese) Countergambit: 1.e4 e5 2.Bc4 f5; ECO Code C23.
See again the above ECO Code lines and compare. See that Berlin Defense variation, which is the main one of Bishop's Opening is ECO Code C24, and the rest variations of Bishop's Opening are ECO Code C23...
On the next lesson, we will learn why you should know the ECO Codes of the main chess openings. Its name will be ECO Codes of the Main Openings.
To see all chess opening lessons, click the following link:
• Chess Opening Sitemap - See All Lessons
The next chess opening lesson is Lesson 18 (ECO Codes of the Main Openings).
