| 976 / | HD | NUCLEAR TECHNOLOGY |
| DIG 355 | DD | SHIELDED CELLS OR ROOMS [G21F-7/00] {5} |
| DIG 359 | | .~ Observation devices permitting vision but shielding the observer (e.g., window, periscope) [G21F-7/02] {1} |
| DIG 360 | DD | .~.~> Windows (e.g., shielded) [G21F-7/02B] |