R Restricted (filme de ação)
R Rolemaster
RA Regular Army
RA Research Assistant
RA Royal Academy
RAAF Royal Australian Air Force
RACE Random Access Card Equipment
RACEP Random Access and Correlation for Extended Performance 
RAD Radiation Absorbed Dose
RAD Rapid Access Disk
RADAR RAdio Detection And Ranging
RADM Rear ADMiral
RAF Royal Air Force
RAM Random Access Memory (R/W)
RAM Red Academicia de Mexico (Mexican Academic Network)
RARDE Royal Armaments Research and Development Establishment
RARE R\'eseaux Associ\'es pour la Recherche Europ\'eenne (the European Organization of Research Networks)
RAS Reliability, Availability, and Serviceability
RASC Residence Account Service Center
RATS Radio Amateur Telecommunications Society
R&B Rhythm and Blues (comumente R and B)
RBC Red Blood Count
RBI Runs Batted In
RBOC Regional Bell Operating Company
RC Red Cross
RC Regional Center
RC Resistor-Capacitor circuit (como em filtros)
RC Roman Catholic
RCA Radio Corporation of America (nome de companhia)
RCAF Royal Canadian Air Force
RCAS Reserve Component Automation System
RCC Radio Common Carrier
RCMP Royal Canadian Mounted Police
RCS Reaction Control System (Espacial)
R&D Research and Development (comumente R and D)
RD Rural Delivery
RDA Remote Data Access
RDBMS Relational DataBase Management System
RDF Radio Direction Finding
REA Rail Express Agency
RECON Reconnaissance
REM Rapid Eye Movement
REO R. E. Olds
REO Removable, Erasable, Optical
RETMA Radio (às vezes equipamento e também Associação de Manufaturas)
REXX Restructured EXtended eXecutor
RF Radio Frequency
RF Radio Frequency (Espacial)
RFC Request For Comments (ARPA Internet)
RFD Rehoboth (MA) Fire Department
RFD Rural Free Delivery
RFI Radio Frequency Interference
RFI Radio Frequency Interference (Espacial)
RFP Request for Proposal
RFQ Request for Quote
RFS Remote File System
RGB Red Green Blue
RGP Raster Graphics Processor
RH Right Hand
RHC Regional (Bell) Holding Company
RHS Right Hand Side
RI Rhode Island
RIACS Research Institute for Advanced Computer Science (NASA)
RIACS Research Institute for Advanced Computer Science (Espacial)
RIAS Radio In the American Sector, Berlin
RIF Reading Is Fundamental
RIF Reduction In Force
RILM Repertoire International de Literature Musicale
RIP Rest In Peace (or Requiescat In Pace : latin)
RIP Routing Interchange Protocol
RIPE R\'eseaux IP Europ\'eenne (European IP Networks) (RARE, q.v.)
RISC Reduced Instruction Set Computer
RITA Recognition of Information Technology Achievement award
RJE Remote Job Entry
RLC Resistor Inductor Capacitor
RLG Research Libraries Group
RLIN Research Libraries Information Network (executado por RLG (q.v.))
RLL Run Length Limited
RMA Radio Manufacturers' Association
RMA Return Materials Authorization
RMATS Remote Maintenance Administration and Traffic System (Telefonia)
RMS Remote Manipulator System (Espacial)
RMS Richard M. Stallman
RMS Root Mean Square
RMS Royal Mail Ship
RN Registered Nurse
RN Royal Navy
RNA RiboNucleic Acid
RNGC Revised New General Catalog (Espacial)
RNZAF Royal New Zealand Air Force
ROFF Run-OFF
ROG Receipt Of Goods
ROM Range Of Motion (Medicina)
ROM Read-Only Memory
ROM Rupture Of Membrane 
ROSAT ROentgen SATellite (Espacial)
ROSE RATS (q.v.) Open Systems Environment
ROSE Remote Operations Service Entity (por ISO/CCITT camada 7)
ROTC Reserve Officers' Training Corps
ROTS Rotary Out Trunks Selectors
ROYGBIV Red, Orange, Yellow, Green, Blue, Indigo, Violet
RPC Remote Procedure Call
RPG RePort Generator
RPG Role Playing Game
RPI Rensselaer Polytechnic Institute
RPM Revolutions Per Minute
RPN Reverse Polish Notation
RPO Railway Post Office
RPS Revolutions Per Second
RPV Remotely Piloted Vehicle
RQ RuneQuest
RR RailRoad
RR Route Relay
RR Rural Route
RRO Rate and Route Operator (Telefonia)
RS Recommended Standard (EIA)
RS Recording Secretary
RS Revised Status
RS Right Side
RS Royal Society
RSCS Remote Spooling Communications Subsystem
RSFSR Russian Soviet Federated Socialist Republic
RSN Real Soon Now
RSU Remote Switching Unit
RSV Revised Standard Edition
RSVP Repondez S'il Vous Plait 
RSWC Right Side up With Care
RT RadioTelephone
RT RealTime
RTA Remote Trunk Arrangement (Telefonia)
RTAC Regional Technical Assistance Center (Telefonia)
RTF Rich Text Format
RTFM Read The @!# Manual
RTFM Read The F***ing Manual
RTG Radioisotope Thermoelectric Generator
RTG Radioisotope Thermoelectric Generator (Espacial)
RTLS Return To Launch Site (Shuttle abort mode) [NASA, Espaço]
RTR Ready to Run 
RTR Reel-To-Reel
RTS Request To Send (EIA RS-232-C)
RTTY Radio Teletype
RU Receive Unit
RVD Remote Virtual Disk [MIT]
RW Right Worshipful
RW Right Worthy
RX Receive
Ry Railway
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