An isolinear rod was a type of information storage technology used by the Cardassian Union.

These small rods interfaced with information storage and processing devices used aboard Cardassian starships and other facilities. They were color-coded with labels that corresponded with the particular information to which they pertained. Holosuite programs could be stored on isolinear rods. They could also be used to pass security clearances.

A unique form of Isolinear rods called Optolythic data rods were used to store high security information. They were only produced on an as-needed basis, and information could only be inscribed on them once and could not be altered thereafter. As a result, these data rods had a reputation for being a secure way to store sensitive data. They were extraordinarily difficult to obtain, and nearly impossible to counterfeit.