ORBA - para
- ORBAT
- order of battle
- organic
- Organisation of Petroleum Exporting Countries
- Organization for Economic Co-operation and Development
- Organization for Economic Cooperation and Development
- Organization for Security and Co-operation in Europe
- OSCE
- OSCE activities, institutions, structures and instruments
- OSCE AISI
- OSCE Assistance Group to Chechnya
- OSCE Chairman-in-Office
- OSCE documents
- OSCE High Commission on National Minorities
- OSCE Ministerial Council
