The IBO rating is with a 360gr arrow at 60lbs at 30" draw. AMO rating is a 540gr arrow at 60lbs at 30" draw.
That's only half correct.
IBO speeds are suppose to based on a 350 grain arrow, 70 pound draw weight and 30 inch draw. However manufacturers can sometimes inflate this for marketing. IBO does not have a regulated standard. Some will claim an IBO speed based on 5 grains of arrow weight per pound of draw weight even if the particular bow only goes to 50 pounds or 27 inches draw length.
AMO does have a defined standard at which to rate the speed of a bow which is what gselkhunter posted.