Ya, 2fps for every pound of draw weight......10fps for every inch of draw length.....1" of draw length = 5lbs of draw weight.......fairly standard expectations. But I always laugh when manufacturers rate their bows for long draws as "354fps IBO at 33" draw". IBO is measured at 30", so that bow would be a 324 IBO bow. What they don't print is an equal comparison for the 27" draw bow, which would be "294 IBO at 27" draw"......LOL.
I think Elite use to actually do the best job with this. On their tune chart they had the limb deflection with mod at whatever DL and gave a fps, generally was pretty accurate.
Ibo is really just a speed at 5gr/#. Manufacturers kinda tried to standardize it with a 30" DL. If going by what IBO rules are, on a shorter draw bow you can go lighter than the 5gr/# if you want to a point, so a short DL bow could actually go up in "IBO rating". I haven't seen anyone adopt that yet.
Edit to add-
This is the only thing I have ever seen from the IBO on it. It's not like they independently test bows and give them a rating. Manufacturers just took the rules and said what their bows would shoot at that, and generally chose 30"
III. EQUIPMENT
A. Grains per Pound and Arrow Speed
1. Arrows must weigh at least five (5) grains per pound of the bow’s maximum shooting weight
unless the archer’s equipment qualifies for the exception set out in Paragraph 2 below. Shooting
weight is defined as the bow’s maximum draw or thrust weight, as set up at the time of
competition. A variance of two (2) pounds of draw weight shall be allowed for bow scale
variation. Equipment qualifying in this paragraph (III.A.1) shall have no limit on arrow speed.
2. In the case where an archer’s equipment, when shot at five (5) grains per pound, does not generate
290 fps, that archer may shoot arrows weighing less than five (5) grains per pound. However,
equipment qualifying under this paragraph (III.A.2) shall not exceed an arrow speed of 290 fps.
I could be incorrect, but I can't remember ever seeing anything else from the IBO on it, everything has just been ads from companies, and repeated in print of reviews.