Explanation
In the standard form of , called Standard Algebraic Notation (SAN), the lowercase x appears immediately before the destination square. Nxe5 means that a knight captures on e5; N is the English letter SAN uses for a knight. The notation does not name the captured piece because the position supplies that information.
For a pawn capture, the starting file comes first. A file is a vertical column of the board: exd5 means that the pawn from the e-file captures on d5. The x also appears in an capture even though the removed pawn is not on the capturer's destination square, and it can combine with , as in exd8=Q.
In Portable Game Notation (PGN), the plain-text format for game files, x is required in the standard SAN form of a capture. On a tournament scoresheet governed by the International Chess Federation (FIDE), it may be omitted, so forms such as ed5 also appear. The form with x is the reliable choice when games must move between programs.
Common confusions
The x and the captured piece
The x only announces that a capture occurred. It does not identify the removed piece; that must be read from the position before the move.
Sources
- 1.FIDE Laws of Chess taking effect from 1 January 2023, FIDE
- 2.Standard: Portable Game Notation Specification and Implementation Guide, rec.games.chess contributors, coordinated by Steven J. Edwards
