| 359 / | HD | OPTICS: SYSTEMS (INCLUDING COMMUNICATION) AND ELEMENTS |
| 109 | DF | OPTICAL COMMUNICATION {13} |
| 115 | DF | .~ Multiplex {7} |
| 124 | DF | .~.~ Wavelength division/frequency division (includes scattering, e.g., Raman, Brillouin, etc.) {4} |
| 125 | DF | .~.~.~ Subscriber system {1} |
| 126 | ![]() | .~.~.~.~ Optical source at only one station |