Given that the discussion is on a thread called 'Football 2020-2021' and was about the rules associated with retrospective action for could play in a football match I think it was pretty clear that we were talking about the rules (or laws) of football.
And it was pretty clear that the rule I mentioned was not part of the official rules in question but more of a convention (or tradition, if you like).
So again please can you give me an example of a rule or law in professional football (not the interpretation of rules or laws) that isn't written down.
The one we were discussing.
Whether you call the rule I mentioned a rule, a convention, tradition or whatever, it doesn't alter the point I was making or make me wrong. I suggest you start addressing the arguments instead of fixating on petty points about labelling.