The 3 primary rule sets for chess puzzles

Whenever anyone posts a puzzle in one of the puzzle forums it is likely created on the basis of one of 3 chess rule sets. The 3rd one does double duty for the retrograde field and effectively yields a 4th rule set as well. The 2nd one, by its very nature is the one chess.com should abide by but I am not sure that it does:

1. The official FIDE OTB rules used to play games in a real physical environment with 2 real players and commonly an arbiter to resolve 'issues' during the game. It would typically apply to puzzles taken from a physical game environment like a World Championship. https://handbook.fide.com/chapter/E012023 
2. The official FIDE online rules which would apply to all puzzles taken from online games played on online sites such as chess.com. https://handbook.fide.com/chapter/OnlineChessRegulations
3. The rules in the Codex for Chess Compositition in sofar that they cover the puzzles made to follow the FIDE-rules with minor but necessary adjustments. https://www.janko.at/Retros/Glossary/Codex2015.htm 
4. The rules in the Codex for Chess Compositition in sofar that they cover the puzzles made to follow the FIDE-rules with Retrograde-extensions. Follow the same link as under "point 3".

Note: All The other Codex composition types may be interesting but commonly impossible to manage in chess.com with its FIDE-oriented puzzle interface so we skip them.

What we would all like is when all puzzles play by the same rules but the situation is that they don't. Which places the burden on the puzzle poster to supply additional information for you to know how the puzzles were made when the details of the rules matter!

Table for the ways to get/claim a draw under the various rule sets. What is most remarkable is that The FIDE ONLINE set is identical to the Codex RETRO set for these conditions. Which has interesting consequences. To discuss in a follow-up post.

Note: DP stands for the inclusion of the Dead Position rule. "Draw by agreement" and "stalemate" are uncontroversial and therefore omitted in the table.

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