| 556 / | HD | ORGANIC COMPOUNDS -- PART OF THE CLASS 532-570 SERIES |
| * | DD | ORGANIC COMPOUNDS (Class 532, Subclass 1) {3} |
| 400 | DF | .~ SILICON CONTAINING {19} |
| 410 | | .~.~ Nitrogen attached directly to silicon by nonionic bonding {2} |
| 411 | DF | .~.~.~> Having -C(=X)-, wherein X is chalcogen, bonded directly to the nitrogen |
| 412 | DF | .~.~.~> Plural silicons bonded directly to the nitrogen |