552 / | HD | ORGANIC COMPOUNDS -- PART OF THE CLASS 532-570 SERIES |
* | DD | ORGANIC COMPOUNDS (Class 532, subclass 1) {11} |
293 | DF | .~ Cyclohexadiene having atoms double bonded directly at the 1- and 4- positions (e.g., paraquinones, etc.) {11} |
304 | .~.~ Carbon double bonded directly at the 1- or 4- position |