Internetwork Operating System 
Instructor Operator Station 
Indian Ocean Ship 
Indian Ocean Station 
Input/Output Selector 
Input/Output Supervision 
Input/Output Supervisor 
Institute of Ocean Sciences 
Institute of Oceanographic Sciences 
INTEGRATED OFFICE SYSTEM 
ISDN Operational Software 
Indian Ocean Satellite 
input/output subsystem 
Input/Output System 
Integrated Operational Services 
Integrated Operations Scenario 
International Organization for Standar… 
International Organizations 
Internet Operating System 
Internetworking Operating System 
Inter-Office Section 
Inter-Operability Specifications 
Idle Ordered Sets 
Illinois Orthopaedic Society 
Immediate Office of the Secretary 
impulse oscillation system 
impulse oscillometry 
impulse oscillometry system 
Indian Ocean Survey 
Indian Ocean Tracking Station