Operations Support Systems 
Office of Space Science 
Operations Support System 
Office of Strategic Services 
Open Source Software 
Output Shaft Speed 
Operation Support System 
Operational Support System 
Office of Space Sciences 
Operation Support Systems 
operational storage site 
Operational Support Systems 
Operator Services System 
Orbital Space Station 
Observation System Simulation 
OEX Support System 
Office of Space Station 
Office of Statistical Standards 
Office Support System 
Ontario Secondary Schools 
Operations System Staff 
orbiting space station 
Object Services Standard 
Observation Support System 
Oceaneering Space Systems 
Office of Safeguards and Security 
Office of Support Services 
Office of the Space Station 
Office System Services 
Online Support System