Optical Transmission Section 
Office of Thrift Supervision 
Officer Training School 
Object Transaction Service 
Orbital Test Satellite 
Office of Toxic Substances 
Optical Transport Section 
Organized Track System 
Off The Shelf 
Office of Technical Services 
Office of Technology Services 
Office of Telecommunication Services 
Officers' Training School 
One Touch Support 
one-time source 
Open Training Services 
Operational Technologies and Solutions 
Operational Tests 
Operations Technical Support 
Optical Technology Satellite 
Orbit Transfer System 
Orbital Tracking Station 
Organized Track Systems 
Outer Thermal Shield 
Oahu Telecommunications System 
Occupation Therapist 
Occupation Therapists 
occupational therapists 
Occupational Therapy Studies 
Occurrence tracking system