| 640 - 649 : COMMUNICATIONS | ||
|---|---|---|
| 640 | Communications (Grouped) | |
| 641 | Visual including audio-visual | |
| 642 | ||
| 643 | Audio | |
| 644 | Signals other than visual or audio | |
| 645 | Synchronous clocks | |
| 646 | SCADA | |
| 647 | ||
| 648 | Other types of communications services | |
| 649 | Parts and accessories | |