[Twey]

Sure, I'm not suggesting we need to go into infinite regress for every explanation! I'm saying that you should bear in mind that you _are_ in the middle of an infinite stack, and what is a ‘how’, a ‘what’ or a ‘why’ is just a function of your current position in it relative to the thing you're talking about. In the ID generation code you might want to explain why you're using this weird format here instead of a more standard format (because it needs to be passed to legacy system XYZ). But if you go up a step or two to where the ID is passed to XYZ in code, that ‘why’ has become a ‘what’ — the calling code acts as a ‘specification’ for the behaviour of that ID generation code.