Explanatory notes
… This heading does not cover hydrazine or hydroxylamine themselves or their inorganic salts ( heading 28.25 ) but … (H 2 NNH 2 ) may, by replacement of one or more hydrogen atoms, give derivatives, e.g. (RHNNH 2 ), and (RHNNHR 1 ), … more hydrogen atoms. Nitrosophenols, which are tautomeric forms of quinone oximes, and nitrosoamines, which are …