| 552 / | HD | ORGANIC COMPOUNDS -- PART OF THE CLASS 532-570 SERIES | 
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| * | DD | ORGANIC COMPOUNDS (Class 532, subclass 1) {11} | 
| 502 | DF | .~ Cyclopentanohydrophenanthrene ring system containing {21} | 
| 526 | DF | .~.~ Carbon double bonded directly to the cyclopentanohydrophenantrene ring system {3} | 
| 530 |  | .~.~.~ The carbon is double bonded directly at the 17-position (e.g., fusidic acids, etc.) {2} | 
| 531 | DF | .~.~.~.~> Nitrogen or sulfur containing | 
| 532 | DF | .~.~.~.~> The carbon is a member of an acyclic chain of exactly two carbons (e.g., 3 keto-4,17(20)-pregnadienes, 17-ethylidene-estranes,etc.) {1} |