PER stands for Perth Airport, while ARN stands for Stockholm Arlanda Airport. These codes are often called IATA codes, a set of identifiers established by IATA (International Air Transport Association) that is widely used by airlines and the aviation industry. Stockholm Skavsta Airport (NYO), Stockholm Bromma Airport (BMA), Stockholm Vasteras/Hasslo Airport (VST) are other airports near this flight route and their unique identifiers/IATA codes.