Choctaw Nation Multi-County Library, McAlester, OK - OCLC symbol (OCLC)
Kincardine Branch, Bruce County Public Library, Ontario - Library symbol - National Library of Canada (NLC)
Ohio-Kentucky-Indiana Regional Planning Authority
Okiek - Language code (ETLW)
Oki Island - Japan - Airport symbol (OAG)
Okijuku - Japan - Seismograph station code, US Geological Survey - Closed (SEIS)
Oko Electric Industry Company (SAUS)
Oldenkamp Inc., Hull, IA - Manufacturer code for watercraft hull identification number (USCG)
Open Knowledge Initiative