Retirement Income Specialist 
Remote Installation Services 
Radiology Information System 
Remote Installation Service 
reflector In Space 
Rail Interface System 
Reporting Identification Symbols 
Retroreflector in Space 
Radiation-Induced Segregation 
Radio Investigation Service 
Random Interleaved Sampling 
Raytheon Information Solutions 
RCRA Implementation Study 
reconnaissance information system 
Reference Information Store 
Regulatory Innovations Staff 
remote installation server 
reporting identification symbol 
Request for Information Services 
Reset to Initial State 
resonance ionization spectroscopy 
Rotational Isomeric State 
Aeris Gestion 
Radar Information Service 
Radar Integration System 
radiation inactivation size 
radiation injury score 
Radio Intercom System 
Radio Interface Subsystem 
radioimmunoscintigraphies