Thanks for all the sprited replys. Perhaps someone can post the question to NATO and see if they can throw more light on the code origins. dogowen Perhaps someone can throw some light on the questions I ask below' 1] the code spreads of the flags as they progressed over the years are known [as chronicled in Cpt. Jinmmy Pack's book - 'Nelson's Blood'], but we need to ask the 'whys'' * why were the strings/set chosen in that context of signal flags - ZTM, BX and ZD2&8. Was it a random willy nilly whim of the commander at signal HQ of the day ! I doubt it. * if not random, then we need to establish the significance of each set by flag choice. # ZTN - [original pre-war until 1951] = #BX - [1952 to 1974] = # AD2&8 - [1975 on --- ] = 2] then why, the need for change, for such a frivilous set with no real bearing on the thetre of war in the need for secrecy. DOGOWEN Copied from blogs (original entry) - post comments here.