Buoyancy Control must be taught at the OW Level and when you hand them that card that is one thing that that card means. The card means many things, and one thing it means is, "This Diver Can Control His/HEr Buoyancy. So, if you are in an organization that gets a funny look when one of its instructors asks, "Hey, Joe, come on and join us in such-and-such-a-divers associate-etc!" That funny look he or she is getting is based on years of experience diving next to "SASADEA-Etc" divers who couldn’t control their buoyancy, whose dive organization put buckets full of divers like that over reefs, and whose agency sold its soul at the Underwater Cross-Roads to you-know-who to get as much money as possible for its franchise when its franchise over there could cares 1% for the marine eco-system. Those "funny" looks are hard earned. OW training must teach "Control of the BC," with mastering it being more subjective, but controlling that BC is about life - either the lives of the creatures in the marine environment or the lives of the divers who are entering the water. The Open Water Card means the diver can control his or her buoyancy. That is one thing that the card means because if the diver cannot control it, that diver is not safe, and then there is obviously no point in taking the course in the first place.