| 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} |
| 57 | DF | .~.~ Chromium, molybdenum, or tungsten containing (Cr, Mo, or {2} |
| 58 | | .~.~.~ Carbon bonded directly to the metal {1} |
| 59 | DF | .~.~.~.~> Chalcogen double bonded directly to the carbon (e.g., molybdenum pentacarbonyls, etc.) {1} |