The R. O. C. is an alternative form of ROC.

I need to buy a new DVD-R machine.

I have two DVD-R machines in my office.

R. I. S. stands for Regional Information System.

The R. I. S.s are conducting an investigation.

T. R. H. stands for Their Royal Highnesses.

D. R. Congo is a country in Central Africa.

D. R. C. is an alternative form of DRC.

Please RSVP by Friday.

Please R. S. V. P. by Friday.