24 February 2023

Chess.com's Game Review Tools PGN

Last week, in Chess.com's Game Review Tools (February 2023), I developed the chart shown on the left (see that post for a larger version of the chart as well as the codes used to identify the different boxes). Because all names in computerdom eventually reduce to an acronym, let's use GRT to mean 'Game Review Tools'.

Since you're reading this post, you're probably interested in analyzing your games and you're undoubtedly aware that chess games are nearly always recorded in a format called 'Portable Game Notation' (PGN). It follows that the different boxes in the GRT chart offer downloads in PGN format.

Specifically, the boxes coded '02, 03a, 03b, 05a, 05b' all have a download, aka 'Share', option. Are the downloads all the same? No, they aren't, but the differences between them aren't enormous and the rest of this post is to discuss their similarities and the differences.

A Chess.com pop-up window like the one shown below appears when you click a 'Share' option. This particular example is from the GRT window coded '03b' in the previous post.

Along with the link for the URL of the game analysis, the pop-up offers functions for posting it to various social media platforms, plus functions for saving the current game in other formats like 'Image', etc. The lower portion of the pop-up, with the background in White, is specific to the PGN function.

The first PGN box, titled 'FEN' is a character string that describes the essential elements of the current position in text format. It is recognized by most chess software. This particular example is for the chess960 start position 'NRKQRBBN'. Its initial castling option are, of course, all available and are shown by the characters 'EBeb'.

Just below the 'FEN' string, to the right of the 'PGN' title, is a series of icons for tailoring the format of the PGN. They are:-

  • Annotation
  • Computer Analysis

  • Highlights
  • Comments, and
  • PGN Timestamps.

The first two icons are selected by a circle, indicating that they are mutually exclusive. The last three icons, which apply to the 'Annotation' icon, are selected by a square, indicating that they can be combined. I haven't tried all of the icons, but they are related to info/data visible via various GRT windows.

The chart box coded '02' has only the icon for 'PGN Timestamps' (default = 'no'). An example of the PGN output -- only moves, without variations or notes-- was shown near the end of the most recent post on my chess960 blog Chess.com Pinpoints a Tactical Error (February 2023). The other PGN functions are added as the 'Review' (chart box '03a') and 'Analysis' ('03b') tabs are invoked from '02'.

The PGN produced by the two chart boxes coded '05a' and '05b' is similar to '03a' and '03b'. The biggest differences are in the many tags (e.g. '[Event "Let's Play! - Chess960"') that make up the PGN header section. There are smaller differences in the moves themselves, but these aren't worth mentioning for now. Maybe later, maybe not; there is already much to explore here...

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