| Ettevõtte nimi | Reg. kood |
|---|---|
| OP SYSTEMS OÜ | 14657436 |
| OPSKAP SYSTEMS OÜ (endine nimi ASKOL HEALTH OÜ) | 17084604 |
| OPSITIO SYSTEMS OÜ | 17304425 |
| OPENLINK SYSTEMS OÜ kustutatud | 14336703 |
| OPTIGROUP SYSTEMS OÜ | 11324881 |
| OPSERVIS SYSTEMS OÜ UÜ kustutatud (endine nimi IceSales OÜ) | 12090936 |
| OPTIMISTIC SYSTEMS OÜ | 17383241 |
| COHEN FARGA OÜ (endine nimi Options Algorithmic Systems Research Company OÜ) | 11396490 |
| OPEN SYSTEMS CONSULTING OÜ | 16553403 |
| NORTHERN OPTICAL SYSTEMS OÜ | 17389746 |