| Acronyms | Meaning / Significance | Source |
| O&M | operation and maintenance | |
| O/R | Originator/Recipient | |
| OA | Office Automation | |
| OA&M | operations, administration and maintenance | AC/317(WG/2)WP/94 |
| OAM | Operation, Administration and Maintenance | |
| OAP | operator assistence position | |
| OAS | Offensive Air Support | |
| OAS | office automation system | |
| OASIS | Open ATM System Integration Strategy | |
| OAT | Operational Air Traffic | |
| OBTM&M | on board test, monitor and maintenance | |
| OCA | offensive counter air | |
| OCA | operational control authority | |
| OCM | Office of the Center Manager | |
| OCO | operating control organisation | AC/317(WG/1)N/610 |
| OCO | Operations Control Organisation | |
| OCR | optical character reader | |
| OCR | Optical Character Recognition | |
| ODA | office document architecture | |
| ODBC | open data base connectivity | ACE ACCIS core cap specs |
| ODC | Office of the Division Chief | |
| ODI | open data-link interface | |
| ODIF | office document interchange format | |
| ODL | office document language | |
| ODP | open distributed processing | |
| ODS | Operator Input and Display System | |
| ODT | operational data typ | data management |
| OEW | operational emergency in war | |
| OI | Area of Operational Interest | |
| OIER | Operational Information Exchange Requirement | |
| OII | Object of Intelligence Interest | |
| OII | operations/intelligence interface | |
| OIW | Open systems Implementation Workshop | |
| OJT | On-The-Job Training | |
| OLDI | On-Line Data Interchange | |
| OLFAPS | operations/logistics functional area prototype system | Ex Strong Resolve 95 |
| OM | OSI Management | |
| OM-55 | ECCM - modem used in SATCOM | |
| OMG | object management group | |
| öMilFs | örtliche Militärische Flugsicherung | |
| OMNIPoint | open management interoperability point | |
| ONS | office of NATO standardization | |
| ONS | Old NADGE Sites | |
| ONST | outline NATO staff target | |
| OOA | out of area | |
| OOTW | operations other than war | CAX |
| OPD | Outline Phsical Design | |
| OPR | Office of Primary Resonsibility | |
| OPREP | operational report | |
| OPS | operational division | NATO IMS |
| ORACLE | overall review of ACCS in a CFE limited environment | |
| ORBAT | Order of Battle | |
| ORC | operational requirement for communications | |
| ORCAM | Originating Region Code Assignment Method | |
| ORCAP | overall review of CNAD activities and projects | 2-annually |
| ORD | Operational Requirements Document | |
| ORTP | operational readiness test programme | |
| OS | operating system | ACE ACCIS core cap specs |
| OSA | open systems architecture | |
| OSAT | overall system acceptance testing | |
| OSC | operational system control | |
| OSCE | organisation for security and co-operation in Europe | |
| OSCRL | Operating System Command and Response Language | |
| OSE | open system environment | ACE ACCIS core cap specs |
| OSE-RM | open systems environment - reference model | |
| OSF | open software foundation | ACE ACCIS core cap specs |
| OSI | open systems interconnection | ACE ACCIS core cap specs |
| OSIE | Open Systems Interconnection Environment | |
| OSM | Overall system Modell | |
| OSP | Overall Strategic Priorities | |
| OSPF | Open Shortest Path First | IETF |
| OSS | one stop shopping | ALLA |
| OSS | Operational Support System | |
| OSS | Operator Subsystem | |
| OSS | Overall System Specification | |
| OTAM | off-the-air monitor | |
| OTC | officer in tactical command | |
| OTE | Hellenic RPO | |
| OTH | over-the-horizon | |
| OTS | Of the Shelf | |
| OTS | open systems interconnection transport service | STC CSNI final report 22/9/95 |
| OU | operating unit | OCO |
| OWG | one-way gateway |
Last Updated on Sep 23, 1999
By NC3ABE
By NC3ABE