ORDVAC - Ordonance Variable Automatic Computer

ORI - Online Retrieval Interface

OROM - Optical Read Only Memory

ORP - Optimal Routing Problem

ORS - Output Record Separator

OS - Open System

OS - Operating System

OS/1 - Operating System 1

OS/2 - Operating System 2

OS/E - Operating System / Environment

OSA - Open System Architecture

OSA - Open Solution Architecture

OSA - Object - oriented System Analysis

OSA - Open Scripting Architecture

OSD - OEN Software Description

OSD - Operating System Dependent

OSD - Office of the Secretary of Defence

OSD PSA - "Office of the Secretary of Defence

OSE - Output Sensitivity Equation

OSF - Open Software Foundation

OSI - Open System Interconnection

OSIRM - Open System Interconnection Reference Model

OSL - Optical System Language

OSL - Object Server Language

OSM - Object Server Maker