A transponder code was a signal burned into the starship's sublight engines that transmitted the ship's name, type, owner, and other pertinent data. For most of the galaxy's history, the Bureau of Ships and Services issued and tracked transponder codes.
In use since the beginning of spacefaring societies, transponder codes could be duplicated or removed, though the procedures involved were difficult, expensive, and highly illegal. Ships without transponder codes could not travel in civilized systems without attracting intense scrutiny.
Some starships, like the Millennium Falcon, had multiple transponder codes that allowed the ship to have multiple identities.
An Identify Friend/Foe transponder, also known as an identification-friend-or-foe transponder or IFF transponder, was a military-specific type of transponder signal that would broadcast the ship's affiliation in addition to the standard data. Some automated ships used IFF broadcast streams to dictate their actions. The automated war cruiser Valiant defended Rogue Squadron pilot Tycho Celchu when he recalibrated his IFF transponder to broadcast the same beacon used by the Another Chance. IFF transponders could also be used to trick enemies into firing on each other by using an IFF transponder scramble command.
- Cracken's Rebel Field Guide
- Star Wars Gamemaster Screen, Revised
- Pirates & Privateers
- Platt's Smugglers Guide
- Hero's Guide
- The Complete Star Wars Encyclopedia
- Millennium Falcon Owners' Workshop Manual