| 546 / | HD | ORGANIC COMPOUNDS -- PART OF THE CLASS 532-570 SERIES | 
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| * | DD | ORGANIC COMPOUNDS (Class 532, Subclass 1) {1} | 
| * | DD | .~ HETEROCYCLIC CARBON COMPOUNDS CONTAINING A HETERO RING HAVING CHALCOGEN (I.E., OXYGEN, SULFUR, SELENIUM, OR TELLURIUM) OR NITROGEN AS THE ONLY RING HETERO ATOMS (Class 540, subclass 1) {1} | 
| 1 | DF | .~.~ Hetero ring is six-membered consisting of one nitrogen and five carbons {24} | 
| 268.1 | DF | .~.~.~ Additional hetero ring containing {4} | 
| 281.7 | DF | .~.~.~.~ Ring oxygen in the additional hetero ring {2} | 
| 283.4 |  | .~.~.~.~.~ The additional hetero ring is five-membered {4} | 
| 283.7 | DF | .~.~.~.~.~.~> Plural ring oxygens in the additional hetero ring | 
| 284.1 | DF | .~.~.~.~.~.~> Polycyclo ring system having the additional hetero ring as one of the cyclos | 
| 284.4 | DF | .~.~.~.~.~.~> Chalcogen attached directly to the additional hetero ring by nonionic bonding | 
| 284.7 | DF | .~.~.~.~.~.~> Nitrogen or -C(=X)-, wherein X is chalcogen, attached directly to the additional hetero ring by nonionic bonding |