IR is used by the pitching gurus on DFP, but most pitching coaches are unfamiliar with the term unless they have been on this website. Denny Tincher uses the term "fluid dynamics", but it is essentially the same thing. Learn what to look for when watching a lesson and you can quickly identify the HE vs. IR instructors. You also have to be aware that there are instructors who throw/demonstrate IR, but teach HE - like Jenny Finch.