| 204 / | HD | CHEMISTRY: ELECTRICAL AND WAVE ENERGY |
| * | DD | PROCESSES AND PRODUCTS {7} |
| 157.15 | DF | .~ Processes of treating materials by wave energy {6} |
| 157.6 | DF | .~.~ Process or preparing desired organic product containing at least one atom other than carbon and hydrogen {16} |
| 157.94 | DF | .~.~.~ Halogen product produced {5} |
| 157.98 | DF | .~.~.~.~ Unsaturated product {1} |
| 157.99 | | .~.~.~.~.~ Unsaturation in aryl ring |