Is there a single list of rules governing Stack Exchange sites (and if so, whre is it?)? More specifically, I'm interested in hard rules that are automatically enforced by the machine, or well-delimited rules that moderators are expected to follow? This is inspired by having seen questions that are notated (under review) "This question is too old to migrate" -- which suggests a rule. I also understand that there is a limit on the number of custom reasons a Beta site can have for closing questions. I basically am interested in rules embodied in the code, but extend that to rules that moderators have to enforce, in case it's too hard to write code to do it automatically. I am totally not asking about rules defining good and bad questions.