Scramble code 1477 represented an encryption method employed by the Galactic Republic for the purpose of secure, confidential communications.
In the time leading up to the Mission to Skytop Station which occurred in 22 BBY, Jedi General Anakin Skywalker discovered the clandestine Separatist listening installation known as Skytop Station, positioned in orbit around Ruusan 2. He then directed the Astromech droid R3-S6 to utilize scramble code 1477 as a means of contacting the Jedi Obi-Wan Kenobi without alerting those at the station. Skywalker communicated his findings to Kenobi, who ultimately instructed him to infiltrate the Separatist outpost. Later, R3-S6, revealed to be a Separatist operative, contacted General Grievous and divulged information regarding the Jedi's unauthorized entry.