| 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} |
| 118 | | .~.~ Zinc, cadmium, or mercury containing (Zn, Cd, or Hg) {3} |
| 119 | DF | .~.~.~> Sulfur double bonded directly to chalcogen {1} |
| 121 | DF | .~.~.~> Carbon bonded directly to the metal {3} |
| 130 | DF | .~.~.~> Chalcogen bonded directly to the metal {2} |