| 552 / | HD | ORGANIC COMPOUNDS -- PART OF THE CLASS 532-570 SERIES | 
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| * | DD | ORGANIC COMPOUNDS (Class 532, subclass 1) {11} | 
| 208 | DF | .~ Polycyclo ring system containing anthracene configured ring system having at least one double bond between ring members and having oxygen single bonded or any atom double bonded directly at the 9- and 10-positions (e.g., anthraquinones, etc.) {19} | 
| 236 |  | .~.~ Nitrogen bonded directly at beta position (i.e., 2-, 3-, 6- or 7-position) {1} | 
| 237 | DF | .~.~.~> Oxygen, nitrogen or additional carbon bonded directly to the nitrogen |