Input (grade 6): The following alpha-3 codes can be user-assigned: AAA to AAZ, QMA to QZZ, XAA to XZZ, and ZZA to ZZZ.
Output (grade 8): The following alpha-3 codes can be user-assigned: from AAA to AAZ, from QMA to QZZ, from XAA to XZZ, and from ZZA to ZZZ.