| Country | Action | Action Date | Effective Date |
|---|---|---|---|
| Australia | Extension | 26/07/1921 | |
| Canada | Extension | 26/07/1921 | |
| CZECHOSLOVAKIA | Signature | 10/08/1920 | |
| CZECHOSLOVAKIA | Ratification | 01/08/1921 | |
| FRANCE | Signature | 10/08/1920 | |
| India | Extension | 26/07/1921 | |
| ITALY | Signature | 10/08/1920 | |
| JAPAN | Signature | 10/08/1920 | |
| New Zealand | Extension | 26/07/1921 | |
| ROUMANIA | Accession | 28/10/1920 | |
| SERB-CROAT-SLOVENE STATE | Accession | 06/08/1921 | |
| South Africa | Extension | 26/07/1921 | |
| UNITED KINGDOM | Signature | 10/08/1920 | |
| UNITED KINGDOM | Ratification | 26/07/1921 |