Rating code

From Memory Alpha, the free Star Trek reference

The rating code is the Romulan equivalent of a personal ID card or credentials.

When it was doubted that Admiral Alidar Jarok was just the low level logistics clerk Setal, the Romulan offered to show the crew of the USS Enterprise-D his rating code to prove that he was Jetal. Worf however claimed that these codes could easily be forged by a spy. (TNG: "The Defector")