1931 Country Prefixes
| United States of America | N | |
| British Empire | G | |
| France | F | |
| Italy | I | |
| Japan | J | |
| Canada | CF- to CK- or G-C | |
| Switzerland | CH- | number |
| Germany | D- | number |
| Hungary | H-M | |
| Czechoslovakia | L-B or OK- | |
| Spain | M-A to M-N | |
| Norway | N- | number |
| Belgium | OO- | |
| Denmark | OU-, OV-, OX-, OY-, OZ- | |
| Netherlands | PH- | |
| Dutch East Indies | PK- | |
| Sweden | SE- | |
| Poland | SP-, SQ-, SR- | |
| Saar Territory | TS- | |
| Kingdom of Serbs, Croats and Slovaks | UN- | |
| Australia | VH- to VM- or G-AU | |
| India | VT- | |
| British Territories | VO-, VP-, VQ-, VR- | |
| South Africa | ZS-, ZT-, ZU- |