From my text, parenteral is a route "other than alimentary canal" (e.g. intraosseus, intravenous, intra-arterial, intramuscular, mucosal), nonparenteral consists of oral and inhalation, and enteral is gastric feeding tube, oral, or rectal. I'm confused as to the relationship of "nonparenteral" and "enteral". Is one a subset of the other or what? If parenteral is non enteral, then isn't nonparenteral non non enteral which would be the same as enteral?