Also the APHA (American Paint Horse Assoc.) put a rule in place in stating to be registered APHA Paint, the applicant horse must have one APHA registered parent. (The other parent could be registered APHA, AQHA, or TB.) This means that APHA no longer registers 'cropout' QHs or TBs, unless at least one parent is already dually registered with APHA.
Pinto DOES have a few limitiations-- they don't register stallions unless both parents are registered with them or an approved breed, and as has been mentioned, they don't allow horses with appaloosa coloring/known breeeding, and they don't allow the general run draft-- however they did just open a division for Gypsy/Drum horses.