With regard to the second and/or third letters in the prefixes in the list below, if the country in question is allocated all callsigns with A to Z in that position, then that country can also use callsigns with the digits 0 to 9 in that position. For example, the United States own KAA - KZZ, and therefore can also use prefixes like KA1, KP4, K5, K9 and so on. The USA also owns AAA - ALZ and can therefore use AL4, AL8 etc., but can NOT use A4 or A9 as they do not own the whole of AA to AZ — they only have AA to AL.
~Note 1: Series allocated to an international organization.
~Note 2: Provisional allocation in accordance with No. S19.33:
(S19.33 Between radiocommunication conferences, the Secretary-General is authorized to deal with questions relating to changes in the allocation of series of call signs, on a provisional basis, and subject to confirmation by the following conference).
