| Code | Name | Region |
|---|---|---|
| ROPRA | Petrila, Hunedoara | HD |
| ROPEI | Petrosani | |
| ROPIN | Piatra Neamt | |
| ROPIA | Piatra Olt | |
| ROOJD | Ojdula | CV |
| ROTM5 | Olosag | TM |
| ROOLT | Oltenita | CL |
| ROROI | Onesti | IS |
| ROOSI | Onesti, Bacau | BC |
| ROOPR | Oprisor | |
| ROOMR | Oradea | |
| ROORA | Orastie | HD |
| ROOVA | Oravita | CS |
| ROORT | Orlesti | VL |
| ROODL | Orodelu | |
| ROORV | Orsova | MH |
| ROOSA | Ortisoara | TM |
| ROOTI | Otopeni | IF |
| ROOTP | Otopeni Apt/bucuresti | IF |
| ROOVI | Ovidiu | CT |
| ROPAD | Padureni | CJ |
| ROPAO | Palota | BH |
| ROPNC | Panciu | |
| ROPAN | Panic | SJ |
| ROMUS | Musca | AB |
| RONDB | Nadab | |
| RONAD | Naidas | |
| RONDI | Navodari | |
| RONAZ | Nazna | MS |
| RONDE | Nedelea | PH |
| RONEV | Negru Voda | |
| RORZW | Nehoiu | BZ |
| RONIB | Nicolae Balcescu | |
| RONIN | Nicolina | |
| RONCL | Niculitel | TL |
| RONFN | Nifon | TL |
| RONVA | Novacu | GJ |
| ROOAR | Oarda De Sus | AB |
| ROOAJ | Oarja | AG |
| ROOCM | Ocna Mures | AB |
| ROOBE | Odobesti | VN |
| ROOSE | Odorheiu Secuiesc | HR |
| ROOGI | Oglinzi | NT |
| ROOTZ | Oituz, Bacau | BC |
| RORZN | Mintia | HD |
| ROENI | Mioveni | AG |
| ROMRA | Mirila | OT |
| RORZA | Mizil | PH |
| ROMAV | Moara | PH |
| ROMSA | Mogosoaia | B |