Joint Aviation Requirements

The Joint Aviation Requirements (JAR) were a set of common comprehensive and detailed aviation requirement issued by the Joint Aviation Authorities, intended to minimise Type Certification problems on joint ventures, and also to facilitate the export and import of aviation products. They were recognised by the civil aviation authorities of participating countries as an acceptable basis for showing compliance with their national airworthiness codes.

Source: Wikipedia — Joint Aviation Requirements (CC BY-SA 4.0)