What does R... stand for?

What does R... mean?

R	Reciprocal Academic & Science » Mathematics
R	Reprint Community » Media
R	Result Academic & Science » Physics
R	Redux Academic & Science » Chemistry
R	Revolution Governmental » Military
R	Report Governmental » US Government
R	Rex Miscellaneous » Names and Nicknames
R	Re-tell Community » Media
R	Refinement Academic & Science » Chemistry
R	Ohm Miscellaneous » Unit Measures
r...	remote (e. g. rsh = remote shell) Computing » Unix Commands
R	Released Governmental » Police
R	Yaw Rankine Rate Governmental » NASA
R	Roentgen Governmental » NASA
R	Rehydratable Governmental » NASA
R	Regulate Governmental » NASA
R	Receive Governmental » NASA
R	Rear Governmental » NASA
R	Rankine Governmental » NASA
R	Range Rate Governmental » NASA
R	Ideal Gas Constant (8.314 joules per Kelvin) Academic & Science » Chemistry
R	Riser Academic & Science » Architecture
R	Rifle Governmental » Military
R	Rhode Island State Library, Providence, Rhode Island Library Symbol Academic & Science » Libraries
R	Returning Governmental » Transportation