Return fare Two-letter country codes Usually at the end of the code, except if followed by "CH" or "IN" Fare bases often end with two-letter country codes. This will be the case when an airline has an international fare in both directions. For example, a fare from Great Britain to Australia may be YE3MGB, and YE3MAU from Australia to Great Britain.[5] This allows the fare to have similar rules, but may have some variations in change fees or to comply with local trade restrictions.