Explanatory notes
… 28.50 ‑ Hydrides, nitrides, azides, silicides and borides, … elements : oxygen ( headings 22.01 , 28.45 , 28.47 and 28.53 ), nitrogen ( headings 28.11 , 28.14 and 28.25 ), phosphorus ( heading 28.53 ), carbon ( heading 29.01 ), and certain other …