https://codegolf.meta.stackexchange.com/q/7448/8478: solutions need to be fully working
https://codegolf.meta.stackexchange.com/q/7987/8478: otherwise they are subject to deletion
https://codegolf.meta.stackexchange.com/q/4867/8478: newer languages are non-competing
https://codegolf.meta.stackexchange.com/q/2419/8478: Default Program or Function
https://codegolf.meta.stackexchange.com/q/7842/8478: but also REPL
https://codegolf.meta.stackexchange.com/q/1501/8478: functions can be unnamed
https://codegolf.meta.stackexchange.com/q/2447/8478: Input and Output methods
https://codegolf.meta.stackexchange.com/q/4708/8478: Numeric I/O as bytes
https://codegolf.meta.stackexchange.com/q/5343/8478: Numeric I/O in unary
https://codegolf.meta.stackexchange.com/q/2190/8478: truthy and falsy
https://codegolf.meta.stackexchange.com/q/2214/8478: what's a string?
https://codegolf.meta.stackexchange.com/q/8395/8478: is the empty string a valid representation of zero?
https://codegolf.meta.stackexchange.com/q/9064/8478: are booleans integers?
https://codegolf.meta.stackexchange.com/q/4780/8478: solutions may cause errors after solving the task
https://codegolf.meta.stackexchange.com/q/4782/8478: but they have to terminate
https://codegolf.meta.stackexchange.com/q/10808/8478: duplicate answers are allowed
https://codegolf.meta.stackexchange.com/q/273/8478: how to count command-line flags

Challenge-type specific:
https://codegolf.meta.stackexchange.com/q/4877/8478: what's a proper quine?

Unclear consensus:
https://codegolf.meta.stackexchange.com/q/2028/8478: What are programming languages? overruled by https://codegolf.meta.stackexchange.com/q/3610/8478

Honorable mention: https://codegolf.meta.stackexchange.com/q/1061/8478: Standard Loopholes