| 313 / | HD | ELECTRIC LAMP AND DISCHARGE DEVICES |
| 567 | DF | WITH GAS OR VAPOR {24} |
| 637 | DF | .~ With particular gas or vapor {2} |
| 638 | DF | .~.~ With metal vapor {1} |
| 639 | | .~.~.~ Mercury vapor {2} |
| 640 | DF | .~.~.~.~> And rare earth metal {1} |
| 642 | DF | .~.~.~.~> And rare gas |