| 548 / | 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) {4} | 
| 400 | DF | .~.~ Hetero ring is five-membered consisting of one nitrogen and four carbons (e.g., halopyrrolidines, etc.) {20} | 
| 416 | DF | .~.~.~ Polycyclo ring system having the five-membered hetero ring as one of the cyclos {5} | 
| 452 | DF | .~.~.~.~ Bicyclo ring system having the five-membered hetero ring as one of the cyclos (e.g., octahydroindoles, etc.) {7} | 
| 469 | DF | .~.~.~.~.~ The bicyclo ring system consists of the five-membered hetero ring and a benzene ring (e.g., indole, etc.) {10} | 
| 492 |  | .~.~.~.~.~.~ Having -C(=X)-, wherein X is chalcogen, bonded directly to ring carbon of the five-membered hetero ring (e.g., indole-2-carboxylic acids, etc.) {1} | 
| 493 | DF | .~.~.~.~.~.~.~> Hydrogen or additional carbon bonded directly to the -C(=X)- group (e.g., aldehydes,ketones, etc.) |