(21) Tetrahydrocannabinols. Synthetic equivalents of the substances contained in the plant, or in the resinous extractives of cannabis, sp. and/or synthetic substances, derivatives, and their isomers with similar chemical structure and pharmacological activity such as the following:
/\ 1 cis or trans tetrahydrocannabinol, and their optical isomers
/\ 6 cis or trans tetrahydrocannabinol, and their optical isomers
/\ 3, 4 cis or trans tetrahydrocannabinol, and its optical isomers (since nomenclature of these substances is not internationally standardized, compounds of these structures, regardless of numerical designation of atomic positions covered).