| 556 / | HD | ORGANIC COMPOUNDS -- PART OF THE CLASS 532-570 SERIES |
| * | DD | ORGANIC COMPOUNDS (Class 532, Subclass 1) {3} |
| 1 | DF | .~ HEAVY METAL CONTAINING (e.g., Ga, In or T1, etc.) {19} |
| 32 | | .~.~ Nitrogen double bonded directly to carbon {3} |
| 33 | DF | .~.~.~> Carbocyclic ring bonded directly to the nitrogen (e.g., azomethines, etc.) {1} |
| 35 | DF | .~.~.~> Additional nitrogen bonded directly to the carbon or nitrogen {1} |
| 37 | DF | .~.~.~> Chalcogen bonded directly to the carbon or nitrogen (e.g., oximes, etc.) |