This symbol incorporates the semaphore signs for the letters N & D, for nuclear disarmament
The symbol consists of 
the semaphore letters "N" and "D" (for "nuclear disarmament") ... some 
incorporating the new "theta" () ecology symbol derived from combining... [DOC] [TLE] Peace Symbol History - Docs Populi [PAR] A history of the Campaign for Nuclear Disarmament (CND) logo ... that the 
symbol incorporated the semaphore letters N(uclear) and D(isarmament).