| 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} |
| 81 | DF | .~.~ Germanium, tin, or lead containing (Ge, Sn, or Pb) {6} |
| 105 | DF | .~.~.~ Containing -C(=X)X-, wherein the X's are the same or diverse chalcogens {2} |
| 107 | | .~.~.~.~ Nitrogen containing |