Heterocyclic compounds with oxygen heteroatom[s] only (excl. compounds containing unfused furan ring, whether or not hydrogenated, in the structure, and lactones, isosafrole, 1[1,3benzodioxol5yl]propan2one, piperonal, safrole, tetrahydrocannabinols "all isomers", carbofuran, and inorganic or organic compounds of mercury)