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: Each puzzle entry includes the starting FEN, the move sequence to solve it, the puzzle's rating, and "Themes" tags (e.g., fork, pin, mate in 2).

The phrase refers to a popular community-curated dataset where millions of Lichess puzzles are organized into zip files based on their Encyclopedia of Chess Openings (ECO) codes . What the Zip Files Contain

: These are designed for offline training or for use in external chess software (like Scid vs. PC) where users want to drill tactics that arise from their own opening repertoire. Where to Find the Data