| 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} |
| 136 | | .~.~ Ruthenium, rhodium, palladium, osmium, iridium, or platinum containing (Ru, Rh, Pd, Os, Ir, or Pt) {1} |
| 137 | DF | .~.~.~> Nitrogen bonded directly to the metal |