3

I've seen two formats of [%eval] syntax in PGN:

  • [%eval 250,5] meaning white is +2.5 pawn up at depth 5
  • [%eval +0.25] means white is 0.25 pawn up

Is any of those mentioned by some PGN standard? Which one is more popular?

  • 1
    "PGN™" PGN is an acronym. It stands for portable game notation and is not trademarked. – Brian Towers Jun 12 '18 at 17:23
  • No idea how ™ appeared here, I don't even know the shortcut for it (and of course I know the meaning of PGN), thanks for pointing it out. – Michal Jun 12 '18 at 21:23
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The PGN standard is found here; it does not mention the [%eval] syntax at all. It specifies comments starting with [ and ending with ] but no format for what's inside; that means that program are free to export and import these comments the way they want, without necessarily being compatible.

The only other places where evaluation is mentioned in standard, §13.8 and especially §16.2.5.6, centipawns are used (which would favor the first option):

16.2.5.6: Opcode "ce": centipawn evaluation

The opcode "ce" indicates the evaluation of the indicated position in centipawn units. It takes a single operand, an optionally signed integer that gives an evaluation of the position from the viewpoint of the active player; i.e., the player with the move.

It does not mention the ply depth at all.

  • This document mentions %eval and used full pawn syntax, but I don't know how official it is (the header says it is a draft). – Michal Jun 12 '18 at 21:26
  • Well found, but it's just an example of what you could do with comments, it doesn't describe a syntax. – Glorfindel Jun 13 '18 at 7:45
  • If I remember well, operational codes (opcode) are for the EPD format (electronic position description). The [%eval ] code, are used inside comments of moves. – djnavas Jun 15 '18 at 7:04

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