WHAT DOES UNDERWATER NUCLEAR TEST 'UMBRELLA' MEAN?

With test moratoriums within the horizon, American weapons labs rushed out a lot of new styles. A tough deadline for testing was set at midnight (0000 hrs), 31 October 1958, as negotiations were established to start that working day, plus the agenda displays it, with 29 tests executed in Oct, four of them on the final day. A single other test was c