Numeric Annotation Glyphs (NAGs)

Definition

Numeric Annotation Glyphs, commonly abbreviated as NAGs, are standardized numeric codes used in chess notation (especially in PGN files) to represent the familiar annotation symbols such as !, ?, !!, ??, and evaluation icons like += (White is slightly better). Instead of storing a symbol, the notation uses a dollar sign followed by a number (for example, $1 for a good move “!”, $4 for a blunder “??”).

NAGs were introduced to give a language- and font-independent way of annotating games, ensuring that databases, engines, and viewers display consistent annotations even on systems that lack special chess fonts or symbols.

Usage in Chess

NAGs are placed immediately after the move they annotate in a PGN. For example: “1. e4 $1 e5 $1 2. Nf3 $1 Nc6 $1” uses $1 to mark each move as a good one. While NAGs are attached to a move in the PGN, some of them are semantically move evaluations (like ! or ?) and others are position evaluations (like += meaning White is slightly better after the move).

Move-quality glyphs evaluate the move just played (e.g., !, ?, !!, ??, !?, ?!).
Position-evaluation glyphs assess the resulting position (e.g., =, unclear, +=, =+, +/−, −/+, +−, −+).
Special-status glyphs describe conditions (e.g., “only move,” “zugzwang,” “initiative,” “time trouble”).

Why Numeric? Historical and Practical Significance

Before NAGs, annotators used punctuation and specialized symbols (from sources like Chess Informant). But many character sets lacked glyphs such as ⩲ (White slightly better), and printed or digital texts could become inconsistent across platforms and languages. With NAGs, a single, machine-readable code maps to the intended symbol, making it easy for software to convert $14 into “White is slightly better (+=)” or into any localized equivalent. This standardization, popularized by the PGN format in the 1990s, helped chess databases and engines exchange annotated games reliably.

Common NAGs (quick reference)

Exact mappings beyond the core set can vary by software, but the following are widely recognized:

$1 = ! (good move)
$2 = ? (mistake)
$3 = !! (brilliant/very good move)
$4 = ?? (blunder/very poor move)
$5 = !? (interesting or speculative move)
$6 = ?! (dubious move)
$7 = “only move” (forced or sole resource)
$9 = “worst move”

Position-evaluation NAGs often used by engines and databases:

$10 = = (equal/roughly balanced)
$13 = unclear (∞)
$14 = White is slightly better (+=)
$15 = Black is slightly better (=+)
$16 = White is better/advantage (+/−)
$17 = Black is better/advantage (−/+)
$18 = White has a decisive advantage (+−)
$19 = Black has a decisive advantage (−+)

Less-common but useful descriptors:

$22 = zugzwang
$23 = initiative
$24 = attack
$25 = counterplay
$26 = time trouble

Examples

Short opening example (Ruy Lopez) using move-quality and evaluation NAGs:

1. e4 $1 e5 $1 2. Nf3 $1 Nc6 $1 3. Bb5 $3 a6 $6 4. Ba4 $14

3. Bb5 $3 — White’s third move is marked “!!” to illustrate a theoretically strong idea (the Ruy Lopez). In practice, annotators usually use $1 or a comment here; this is just to show the code.
3... a6 $6 — “?!” dubious: driving the bishop can be fine, but carelessly handled it can concede long-term positional targets.
4. Ba4 $14 — After White retreats, many lines leave White with a slight positional pull (+=).

Another snippet highlighting “only move”:

...Qh4+ 2. g3 $7 Qxe4+ 3. Qe2 — Here 2. g3 $7 denotes that 2. g3 is the only move to avoid immediate disaster.

Inline viewer (moves only; NAGs shown in the text above)

The following mini-viewer shows the same opening moves for reference:

How to add NAGs to your PGN

Insert the NAG immediately after the move. You can combine textual comments in braces with NAGs:

1. d4 $1 {Strong central presence} Nf6 $1 2. c4 e6 3. Nc3 Bb4 $5 {The Nimzo-Indian; flexible and dynamic} 4. Qc2 $14 {White keeps the pair of bishops and a slight edge} ...

Most chess GUIs let you pick “!” or “?!” from a menu; they store it internally as the corresponding $-code.
Engines that “annotate” games will often insert NAGs automatically based on evaluation swings (for example, a swing of more than ~2.0 might be marked as a blunder, $4).

Strategic significance

NAGs help readers quickly grasp what the annotator thinks about a move or position without lengthy prose. They serve as teaching beacons in opening theory (flagging critical ideas or novelties), in tactics (marking blunders and brilliancies), and in endgames (describing advantages or features like zugzwang). In databases, NAGs act as searchable metadata, enabling queries like “find positions assessed as += from my repertoire.”

Interesting facts and anecdotes

Chess Informant popularized symbolic annotations (like ⩲) long before PGN. NAGs made it practical to encode those symbols in plain text.
Some early databases and mailing lists preferred NAGs because many systems could not render special symbols uniformly; $14 (+=) traveled better than a hard-to-print glyph.
Engines sometimes disagree with human annotations: a move long hailed with $3 “!!” in classic books can be revised to $5 “!?” after deep engine analysis.
Modern viewers can localize NAGs: $23 might show as “initiative” in English, “initiative” in French/German, or with a small icon.

Tips and pitfalls

Use NAGs sparingly and consistently; combine them with brief comments to make your annotations educational, not cryptic.
Remember: some NAGs describe the move; others describe the resulting position. Place them after the move that produces the position.
Mappings beyond the core set can differ slightly between programs. If precision matters, check your viewer’s NAG reference.

Numeric Annotation Glyphs (NAGs)