I know you mean that in a snarky way, but I just for clarity: we're talking about programming your editor here, i.e., writing code to extend Emacs' functionalit

I know you mean that in a snarky way, but I just for clarity: we're talking about programming your editor here, i.e., writing code to extend Emacs' functionality, not using Emacs to write some unrelated program - which, of course, you probably do much more often, but then you don't need to look up the documentation we're talking about here.