NAG (Numeric Annotation Glyph)

NAG (Numeric Annotation Glyph)

Definition

NAG stands for Numeric Annotation Glyph. It is a standardized set of numbers, each beginning with a dollar sign (e.g., $1, $2, $10), used to encode the familiar chess annotation symbols like !, ?, ±, and ∞ inside plain-text game records, especially PGN files. NAGs allow authors and software to represent move quality, evaluations, and positional features in a language- and font-agnostic way.

Usage

In PGN, a NAG is attached immediately after the move it annotates. For example, 1. e4 $1 indicates “1. e4!” (a good move). Evaluation NAGs (e.g., $10 for “equal position”) are also appended to moves to describe the resulting position after that move. Chess databases, engines, and viewers read these numeric codes and display the corresponding glyphs (!, ??, ±, =, etc.).

Typical uses include:

• Marking move quality: !! (brilliant), ! (good), ? (poor), ?? (blunder), !?, ?!.
• Summarizing the position after a move: = (equal), ± (White better), ∓ (Black better), +− (White winning), −+ (Black winning), ∞ (unclear).
• Flagging features: initiative, attack, compensation, and other thematic assessments (supported by many viewers).

Common NAGs (move quality)

• $1 = ! (good move)
• $2 = ? (poor move)
• $3 = !! (brilliant/very good)
• $4 = ?? (blunder/very poor)
• $5 = !? (interesting/speculative)
• $6 = ?! (dubious)

Common NAGs (evaluation)

• $10 = = (equal position)
• $11 = ∞ (unclear)
• $12 = ⩲ (White slightly better)
• $13 = ⩱ (Black slightly better)
• $14 = ± (White better)
• $15 = ∓ (Black better)
• $16 = +− (White winning/decisive advantage)
• $17 = −+ (Black winning/decisive advantage)

Note: Many programs support additional NAGs for features like initiative, attack, compensation, development or space advantage, passed pawns, etc., but the above are the most widely used.

Examples

Basic PGN with NAGs (Ruy Lopez opening):

1. e4 $1 e5 $1 2. Nf3 $1 Nc6 $1 3. Bb5 $5 a6 $1 4. Ba4 Nf6 $1 5. O-O $1 Be7 $1 6. Re1 $1 b5 $1 7. Bb3 d6 $10

Explanation: $1 marks several natural, good developing moves; $5 flags 3. Bb5 as “interesting”; $10 after 7...d6 indicates the position is equal.

You can visualize the opening moves here (viewer will show the line; NAGs shown above):

Annotating a tactical shot with NAGs:

...Qh4?? would be written as ...Qh4 $4, marking a blunder. A brilliant sacrifice might appear as 24. Rxd4!! → 24. Rxd4 $3.

Strategic and historical significance

NAGs were popularized with the PGN standard in the early 1990s to solve a practical problem: traditional symbols like ± or ∞ are not reliably portable across fonts, encodings, or languages. Numeric codes ensured that annotations could be exchanged safely in plain ASCII and later rendered as glyphs by chess software. This standardization also enables powerful database features—users can search for “!!” moves or filter games by evaluations like “±”.

Practical tips

• Be consistent: use $1–$6 for move quality and $10–$17 for position evaluations after the move.
• Don’t overuse: a few well-placed NAGs make a game readable; too many can clutter the score.
• Combine with comments: NAGs give the headline (!? or ±); a brief comment explains why.
• Viewer differences: most modern tools agree on the common NAGs above; less common NAGs may render differently depending on the software.

Interesting facts and anecdotes

• NAGs help keep annotations language-neutral: “$14” means “White is better” everywhere, regardless of local notation.
• Engines increasingly suggest human-friendly NAGs (e.g., marking blunders with $4) alongside numeric evaluations to guide study.
• Many classic brilliancies are cataloged with $3 (!!) on the critical sacrifice, making it easy to find spectacular moves in databases.