Universal Postal Union (UPU) Acts

The Acts of the Universal Postal Union (UPU) have the character of multilateral international agreements between the UPU member countries that regulate international postal traffic. The regulations form the basis for the requirements on basic postal services imposed on the Czech postal license holder by the Czech Telecommunication Office (CTO). Some of the UPU Acts also regulate treatment of mail outside the Czech Republic.

(http://www.upu.int/en/the-upu/acts-of-the-union-and-other-decisions/acts-of-current-cycle.html)