Heterocyclic compounds with oxygen hetero-atom[s] only (excl. compounds containing unfused furan ring, whether or not hydrogenated, in the structure, and lactones, isosafrole, 1-[1,3-benzodioxol-5-yl]propan-2-one, piperonal, safrole and tetrahydrocannabinols all isomers') 5 4 3 2 1 0 0