What does rr stand for?

Ragged Right - Typography (BARN)

Rarissime - Very Rarely - Latin (GPO)

Rules (SAFN)

Montserrat - NCIC country-territory code (NCIC)

Pike and Fischer's Radio Regulations - A publication (DLA)

Rack Row (SAUS)

Radar Ranging (SAUS)

Radiation Reaction - Cells - Medicine

Radiation-Resistant

Radiation Response

Radiation Retinopathy - Ophthalmology

Radical Rhythms

Radio Ragulatory (SAUS)

Radio Range

Radio Ranging (SAUS)

Radio Receptor (IAA)

Radio Recognition

Radio Regulation (SAUS)

Radio Regulations

Radio Regulations, Geneva (OTD)

Radio Relay (CINC)

Radio Research

Radio Resource (CGWS)

Radio Resource Management (SAUS)

Railroad - Firearms use code - Firearms collecting (FAUC)

Railroad - GeoNet geographic features code (GEON)

Raised Ranch - Architecture (BARN)

Rallye Racing (SAUS)

Rambler Rogue - NCIC car model code

Rand Rifles - British military (DMA)

Range Rate (NASA)

Range Recorder - NASA (IAA)

Range Rover (SAUS)

Ranging Reticle (SAUS)

Rapid Recording (SAUS)

Rapid Rectilinear

Rarely Reversed - Decisions in law

Raritan River (SAUS)

Raritan River Rail Road Co. - AAR code

Rated Radius - Automotive engineering

Rate Ratio

Rate Rebate - British

Rattus Rattus - The ship or black rat

Ray Rider (SAUS)

Readiness Region - Military

Readiness Reports (SAUS)

Readiness Review (KSC)

Reading Room - Discussion board on TheOneRing.net

Readjustment Regulation (SAUS)

Readjustment Rule - Linguistics (IEL)

Readout and Relay

Read Records (SAUS)

Read-Register (SAUS)

Ready Reckoner (DGA)

Ready Reference

Real Reality (SAUS)

Real Riders - Toy collection

Rear (AABC)

Rear Engine, Rear Drive - Automotive engineering

Rear-engine, Rear-drive - Automotive engineering

Rear Right (SAUS)

Receive Ready - Computer science (IEEE)

Receiver Ready (SAUS)

Receiver Room - Navy (CAAL)

Receiving Report (AAG)

Receptor Regulation - National Institute of Environmental Health Sciences (RCD)

Recipient Rights

Reclaim Rinse (SAUS)

Recoilless Rifle

Recommendation Report (SAUS)

Recommended for Re-Engagement - British

Reconfirmed (TRID)

Record Rarities - Record label

Recovery Reliability (MCD)

Recovery Room

Recreation Room (SAUS)

Recruit Roll - Navy

Recurrence Rate

Rediscount Rate

Red Ramp - Gunnery

Red Reflex - Ophthalmology (DAVI)

Redstone Resources, Inc. - Toronto Stock Exchange symbol

Reduced Range

Redundancy Reduction (AAG)

Reed Relay (SAUS)

Reentry Range

Reference Receiver

Reference Record (SAUS)

Reference Register - Computer science

Reflectors - JETDS nomenclature - Military (CET)

Refreshment Room - Indian Railway (TIR)

Refuel Receiver (SAUS)

Regenerative Repeater (SAUS)

Regional Railroad

Regional Railways - A passenger sector of British Rail (UKR)

Regional Reinforcement (SAUS)

Registered Representative - Wall Street stock salesman

Register Reset (SAUS)

Register to Register (MCD)

Register-to-Register Instruction (IAA)

Register-to-Register Operation (IAA)

Regular Respirations - Medicine (MEDA)

Regular Rhythm - Cardiology (DAVI)

Rehabilitation Record

Relative Rank

Relative Response

Relative Risk - Medicine

Relay Rack - Telecommunications (TEL)

Release Beport (SAUS)

Release Record (SAUS)

Reliability Requirements (SAUS)

Relief Radii (MSA)

Religious Roundtable (EA)

Remington Rand - Commercial firm (NADA)

Remote Request - Computer science (GART)

Removal Rate (AAEL)

Removal-Replacement

Rendezvous RADAR - NASA

Renegotiation Regulations

Renewable Resources

Renin Release - Endocrinology (MAE)

Rent Regulation (Office of Rent Stabilization) - Economic Stabilization Agency - A publication (DLA)

Repeatable Read (SAUS)

Repeatable Runout (SAUS)

Repeatedly Reactive

Repetition Rate

Replacement Rate (SAUS)

Reporting Responsibility (ACAE)

Report Reaching - ICAO (FAAC)

Republic at Romania (BARN)

Request Ready (SAUS)

Required Reserves

Requirements Review - NASA (NASA)

Requirements Review - Automotive engineering

Requisition Restriction Code (DNAB)

Reroute - Telecommunications (TEL)

Rerun Routine (SAUS)

Rescue Raider

Research Reactor - Nuclear energy (IAA)

Research Report

Research Review (SAUS)

Reservatis Reservandis - With All Reserve - Latin

Reserve Regiment - British military (DMA)

Residue Register (IAA)

Resonance Raman

Resource Record

Resource Report

Resource Reservation Protocol (SAUS)

Respiration Rate

Respiratory Rate - Medicine

Response and Recovery Directorate - Emergency Management (EMA)

Response Rate (DAVI)

Response Regulator - Biochemistry

Responsible Receiver

Restart Repeater (SAUS)

Restart Routine (SAUS)

Restrictive Requirement (SAUS)

Result Register (SAUS)

Retired Reserve - Military

Retroreflector (SAUS)

Retro-Rocket - Army (AABC)

Return Rate (IEEE)

Return Register

Revenue Release - A publication (DLA)

Reverse Reading (SAUS)

Reverse Recovery - Electronics

Reverse Reduction (DS)

Reverse Relay (SAUS)

Review for Religious - A publication (BRI)

Revised Report (SAUS)

Revised Reports - Legal - British

Revision Record (MSA)

Revolver Rifle (SAUS)

Rheumatoid Rosette - Medicine (DB)

Rhodesia Regiment - British military (DMA)

Rhymney Railway - Wales

Richey Resources Co. - Commercial firm

Ridge Regression - Statistics

Rifle Range

Right Rear

Right Reverend - Of an abbot, bishop, or monsignor

Right Reversed (SAUS)

Rights Reserved

Rigid Rotor (SAUS)

Rigid-Rotor - Calculations

Risk Ratio

Risk Reduction - Branch - Forecast Systems Laboratory (USDC)

Riva-Rocci Sphygmomanometer - Medicine (DMAA)

Rocket Research (ACAE)

Rodman&Renshaw Cap - NYSE symbol

Rodman & Renshaw Capital Group - NYSE symbol (SPSG)

Roemische Religions-Geschichte - A publication (OCD)

Rollback Routine (SAUS)

Rolling Resistance - Automotive engineering

Roll Radius (MCD)

Roll Roofing (AAG)

Rolls-Royce - Automobile

Rolls Royce Ltd. (SAUS)

Roltback Routine (SAUS)

Ronald Reagan - US president, 1911-

Root Rot - Plant pathology

Rotationally Resolved (SAUS)

Rough Riders - The City of London Yeomanry - Military unit - British

Round Robin (IEEE)

Route Relay (SAUS)

Routine Message Precedence - Telecommunications (ADDR)

Routine Relay (KSC)

Royal Air Force - ICAO designator (AD)

Rubber - Soil biology - Human-introduced crops (QSUL)

Running Reverse

Rural Rehabilitation (SAUS)

Rural Resident (OICC)

Rural Road (SAUS)

Rural Route

Rush and Run (WDAA)

Rush Release

Ruthenium Red - Inorganic chemistry (OA)

Very Rare - Numismatics