It is probable that we have a disagreement about what counts as a "factoid", and maybe it's not a great word to be using ( I took it from the parent), but I do think there are real differences between some things you're conflating. Working within the framework of your example, I think understanding how compilation units and the linker work is far more fundamental than knowing when the the "static" keyword impacts linking and when it doesn't. If I know that I need some way to make my variable visible outside my compilation unit, I can look up the syntax to do it ("factoid"), but if I don't understand how linking works at all, I'm missing a more fundamental mental model. Of course, I absolutely think that a C programmer should know the syntax, it's just less important to remember such things than to understand the model.