One Finger Salute 
Object File System 
Operational Fixed Service 
Orbital Flight System 
Officer Foundation Standards 
Operational Forecast System 
Oracle Federal Systems 
Orbiter Functional Simulator 
Offset 
Orbiter Flight Simulator 
Orbiter Flight System 
Order of Free State 
Out-of-Frame Seconds 
occasions for smoking scale 
Office of Field Service 
Office of Financial Stability 
Office of Food Safety 
Office of Forensic Services 
Office of the Foreign Secretary 
Officer Foundation System 
Oil from Sludge 
oligofructose 
Online Financial Solutions 
Open File Server 
Open File System 
operational flight software 
Operations and Flight Support 
Optical Fiber Solutions 
Optical-Fiber Sensor 
Optical-Fiber Sensors