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 prior to the fall of the Colonies.
While the Aerian merchant code is apparently known to most Colonial military units, the computer program used by Athena to discipher the code does not factor in merchant codes. This continues to be the case 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 initially assumed.
Robber informs Apollo and Boomer that the code was passed down from his Original Sinner, who was an Aerian robber (TOS: "The Long Patrol").