There is a unique overlap in the United States with aircraft having a single number followed by two letters and radio call signs issued by the Federal Communications Commission to Amateur Radio operators holding the Amateur Extra class license. For example, N4YZ is, on the one hand, a Cessna 206 registered to a private individual in California, while, on the other hand, is also issued to an Amateur Radio operator in North Carolina. Since an aircraft registration number is also used as its call sign, this means that two unrelated radio stations can have the same call sign.