These are just IATA (International Air Transport Association) codes. They are used in aviation to identify and differentiate airports. That’s why a Townsville Airport to Dubai Intl Airport flight would often be abbreviated as a TSV to DXB flight. Abu Dhabi Zayed Intl Airport (AUH), Sharjah Airport (SHJ), Dubai Al Maktoum Intl Airport (DWC), Abu Dhabi Bateen Airport (AZI), Ras Al Khaimah Airport (RKT) are some additional IATA codes for airports related to your trip.