The Strasbourg Agreement Concerning the International Patent Classification (or IPC), also known as the IPC Agreement, is an international treaty that established a common classification for patents for invention, inventors' certificates, utility models and utility certificates, known as the "International Patent Classification" (IPC). The treaty was signed in Strasbourg, France, on March 24, 1971, it entered into force on October 7, 1975, and was amended on September 28, 1979. States that are parties to the Paris Convention for the Protection of Industrial Property (1883) may become party to the Strasbourg Agreement. As of March 2021, there were 64 contracting parties to the Strasbourg Agreement. The Holy See, the Iran and Liechtenstein signed the Agreement in 1971 but have not ratified it. See also European Convention on the International Classification of Patents for Invention (1954) References External links Strasbourg Agreement Concerning the International Patent Classification in the WIPO Lex database — official website of WIPO. The full text of the Strasbourg Agreement Concerning the International Patent Classification Patent law treaties Patent classifications World Intellectual Property Organization treaties Treaties concluded in 1971 Treaties entered into force in 1975 1971 in France Treaties of Albania Treaties of Argentina Treaties of Armenia Treaties of Australia Treaties of Austria Treaties of Azerbaijan Treaties of Belarus Treaties of Belgium Treaties of Bosnia and Herzegovina Treaties of the military dictatorship in Brazil Treaties of Bulgaria Treaties of Canada Treaties of the People's Republic of China Treaties of Croatia Treaties of Cuba Treaties of the Czech Republic Treaties of Czechoslovakia Treaties of North Korea Treaties of Denmark Treaties of Egypt Treaties of Estonia Treaties of Finland Treaties of France Treaties of West Germany Treaties of East Germany Treaties of Greece Treaties of Guinea Treaties of Ireland Treaties of Israel Treaties of Italy Treaties of Japan Treaties of Kazakhstan Treaties of Kyrgyzstan Treaties of Luxembourg Treaties of Malawi Treaties of Mexico Treaties of Monaco Treaties of Mongolia Treaties of Montenegro Treaties of the Netherlands Treaties of Norway Treaties of Poland Treaties of Portugal Treaties of South Korea Treaties of Moldova Treaties of Romania Treaties of the Soviet Union Treaties of Serbia Treaties of Slovakia Treaties of Slovenia Treaties of Francoist Spain Treaties of Suriname Treaties of Sweden Treaties of Switzerland Treaties of Tajikistan Treaties of North Macedonia Treaties of Trinidad and Tobago Treaties of Turkmenistan Treaties of Turkey Treaties of Ukraine Treaties of the United Kingdom Treaties of the