Explanatory notes
… the –NH 2 group by acid radicals. This heading excludes , however, urea (H 2 NCONH 2 ), the diamide of carbonic acid, which is principally used as a fertiliser and, even if pure, falls in heading 31.02 or 31.05 . (A) ACYCLIC … (C 14 H 20 ClNO 2 ). This heading excludes , however, heterocyclic ureides, e.g., malonylurea (barbituric …