one- - opti
- one-cycle mode
- one-dimensional array data
- one-shot execution step
- online maintenance
- ONOFF
- ONOFF-G
- onshore processing facilities
- onto support
- OOP
- OPC
- open data base connectivity
- open data definition & access
- open display style console-type HIS
- open drain funnel
- open systems interconnection
- open unified software environment
- Open VMS
- open-wide door
- OpenDDA
- OpenUSE
- operating expenditure
- operating system
- operation and monitoring function
- operation and monitoring window
- operation guide message
- operation mark
- operation pending status register
- operation signal setting area
- operations data system
- operator training simulator
- operator training system
- OPEX
- OPF
- OPHI
- OPLO
- OPMK
- OPP
- opportunity study
- OPS
