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.
- Cracken's Rebel Field Guide
- Star Wars: The Roleplaying Game, Second Edition
- Galaxy Guide 7: Mos Eisley
- "Rebel Privateers!"—Star Wars Adventure Journal 2
- Platt's Starport Guide
- Galladinium's Fantastic Technology (As "transponder signal")
- Alliance Intelligence Reports
- Shadows of the Empire Planets Guide
- Star Wars Gamemaster Screen, Revised
- Cynabar's Fantastic Technology: Droids
- Pirates & Privateers
- Platt's Smugglers Guide
- Hero's Guide
- The Complete Star Wars Encyclopedia
- Millennium Falcon Owner's Workshop Manual
- Star Wars: Edge of the Empire Core Rulebook
- Suns of Fortune
- Fly Casual