The following societies, nations, and/or polities have accepted the "Declaration in lieu of Certification of Citizenship" (DLCC) and the "Declaration in lieu of Certification of Nationality" (DLCN) below...

...both of which are supported by two cases of customary International law [Art. 15 UDHR, Art. 3 MC], and the National laws of at least one UN Member State [(Art. 46 - lettera c) D.P.R. 445/2000]:

Society, Nation, and/or Polity Date Link
Principado Ilhéu da Pontinha 29 July 2013
Principato d'Oriente 31 July 2013
Council of Holon Cinna 9 July 2013

The legal adoption of the DLCC is called the DLCC Document Convention. Other important treaties follow below:

Treaty Link
Great Pacific Garbage Patch Treaty (GPGPT)  
Multi-Oceanic Garbage Patch Treatment (MOGPT)  
Space Debris Treaty (SDT)  
Cyberterra Treaty (CTT)  
Anti-Antarctic Treaty System (AATS)  
Declaration of Washington (OEAS)