Following the decision of the International Radio Telegraph Convention signed in Washington on 25 November 1927
Effective from 1 January 1929 (Resolution 436 of ICAN/CINA)
| Country | Prefix | |
|---|---|---|
| United States of America | K, N or W | |
| British Empire | G or M | |
| France | F | |
| Italy | I | |
| Japan | J | |
| Chile | CA to CE | |
| Canada | CF to CK | |
| Morocco | CN | |
| Portuguese Colonies | CR | |
| Portugal | CS to CU | |
| Roumania | CV | |
| Uruguay | CX | |
| Ireland | EI | |
| Haiti | HH | |
| Siam | HS | |
| Bulgaria | LZ | |
| Czechoslovakia | OK | |
| Belgium | ON to OT | |
| Denmark | OU to OZ | |
| Persia | RV | |
| Sweden | SA to SM | |
| Poland | SP to SR | |
| Greece | SV, SX, SY or SZ | |
| Iceland | TF | |
| Saar Territory | TS | |
| Kingdom of Serbs, Croats and Slovenes | UN | |
| Canada | VA to VG | |
| Australia | VH to VM | |
| Newfoundland | VO | |
| British Colonies & Protectorates | VP to VS | |
| Afghanistan | YA | |
| New Hebrides | YH | |
| Free City of Danzig | YM | |
| Salvador | YS | |
| New Zealand | ZK to ZM | |
| South Africa | ZS to ZU |
The nationality and registration marks borne by aircraft shall be constituted by a group of five letters.
The nationality of the aircraft shall be indicated by the first letter or the first two letters of such group.
A hyphen of a length equal to the width of one of the letters shall be placed immediately after the nationality letter or letters.