RISTA – (a) Reconnaissance, Intelligence, Surveillance, and Target Acquisition (see also ISTAR) RWH – (a) Rain Water Harvesting RJ RJD – (i) Reduced Julian Day RK RKBA – Right to Keep and Bear Arms (Second Amendment to the United States Constitution) RKI – (i) Robert Koch Institute, German governmental research institute in Berlin RKO – (i) Radio-Keith-Orpheum Pictures RL rL – (i) Rontolitre RL – (i) Release Line – Real Life – Ronnalitre RLP – (i) Recognised [Operating/Operational] Land Picture RLS – (i) Restless Leg Syndrome RLY – (p) Rally Point RM RM – see separate disambiguation page rm – (s) Raeto-Romansh language (ISO 639-1 code) RMA – (i) Return Mailing Authorization – Revolution in Military Affairs – Rachel McAdams RMC – (i) Robert Menzies College RMC – (ii) Royal Military College (Australia, Canada, UK) RMDA – (i) Records Management and Declassification Agency RMP – (i) Recognised [Operating/Operational] Maritime Picture RMS – (i) Rate-Monotonic Scheduling – Richard M. Stallman – Root-Mean-Square – Royal Mail Ship (e.g. RMS Titanic) RN rn – (s) Rundi language (Kirundi) (ISO 639-1 code) Rn – (s) Radon RN – (a) Radio Netherlands RN – (i) Royal Navy – Registered Nurse (US) RNA – (i) RiboNucleic Acid RNAD – Royal Naval Armaments Depot (UK) RNPS – (i) Radio Network Planning System RNZ – (a) Radio New Zealand RNZI – (a) Radio New Zealand International RO ro – (s) Romanian language (ISO 639-1 code) RO – (i) Range Only – Red Orchestra – (s) Romania (ISO 3166 and FIPS 10-4 country code digram) ROA – (a/i) Rate Of Ascent ROC – (i/a) Receiver Operating Characteristic (statistics) – Regional Operations Centre – Republic Of China – Roc-A-Fella Records – Regional Organisations of Councils ROCV or ROC-V – (i) Recognition Of Combat Vehicles ("rock-vee") ROD – (a/i) Rate Of Descent – Record Of Decisions – Report Of Discrepancy ROE – (i) Rules Of Engagement roh – (s) Raeto-Romansh language (ISO 639-2 code) ROH – (i) Ring of Honor ROI – (i) Return On Investment, Republic of Ireland. ROME – (a) Return On Modeling Effort ROFL(MAO) – (i) Rolling On the Floor Laughing (My Ass Off) ROFLOL – (i) Rolling On the Floor Laughing Out Loud ROK – (a/i) Republic of Korea ROL – (s) Romanian leu (ISO 4217 currency code) ROM – (a) Read-Only Memory – Refuel On the Move – Royal Ontario Museum ron – (s) Romanian language