Plain English Meaning
The set of rules that decides how route and procedure names are spelled out — which letters and numbers go where, and what each part stands for. It's why airway names like V123 or J45 follow a predictable pattern instead of being random codes.
Full Definition
The standardized rules used by ICAO and the FAA for constructing the alphanumeric codes that identify airways, routes, fixes, and navigation procedures on charts and in flight plans. A designator is built from a defined set of letters, numbers, and prefix/suffix characters, each carrying specific meaning about the type of route or procedure (for example, a single letter indicating the route category, followed by digits identifying the specific route).