| 552 / | HD | ORGANIC COMPOUNDS -- PART OF THE CLASS 532-570 SERIES | 
| * | DD | ORGANIC COMPOUNDS (Class 532, subclass 1) {11} | 
| 502 | DF | .~ Cyclopentanohydrophenanthrene ring system containing {21} | 
| 515 | DF | .~.~ Nitrogen bonded directly to the cyclopentanohydrophenanthrene ring system {3} | 
| 516 | DF | .~.~.~ The nitrogen is double bonded to the cyclopentanohydrophenanthrene ring system {3} | 
| 519 | DF | .~.~.~.~ Oxygen bonded directly to the nitrogen (e.g., oximes, isonitrosos, etc.) {1} | 
| 520 |  | .~.~.~.~.~ The nitrogen is bonded directly at the 3-position |