Aerian merchant code
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The Aerian merchant code is a form of cryptography in use by Aeries merchants for at least 700 yahren.
The Aerian merchant code is apparently not known to most Colonial military units, as Galactica did not have any information on Robber's transmissions back to Aeries. Thus the code is unknown to them until Cassiopeia informs Adama that the coded transmissions that Galactica receives from Recon Viper 1 are, in fact, human in origin, and not Cylon as first assumed (The Long Patrol).