Office of Climate Observation 
One Cancels the Other Order 
Open-Close-Open 
Orbiting Carbon Observatory 
Object Code Only 
Off-Load Control Officer 
Overall Control Office 
Office of Communications and Outreach 
One Cancels the Other 
Oort Cloud Object 
Operational Capability Objective 
Oven Controlled Oscillator 
Obstruction of Court Orders 
Office of Children's Ombudsman 
Office, Chief of Ordnance 
Office, Chief Ordnance 
Officer Commanding Operations 
Operating and Control Organization 
Operating Capital Outlay 
Operation Capability Objectives 
Operational Contracting Officer 
Operational Control Organization 
Operations Control Office 
Orders to Cease Operation 
Ostend Air College