online | Stop Online Piracy Act | World Championship of Online Poker | Toontown Online | Rhapsody (online music service) | ontology | Online game | Online chat | Massively multiplayer online game | Sony Online Entertainment | massively multiplayer online game | Asia Times Online | Ragnarok Online | Online News Association | BBC Online | Ultima Online | T-Online | Star Trek Online | Prodigy (online service) | Phantasy Star Online | Online magazine | Online Copyright Infringement Liability Limitation Act | Massively multiplayer online role-playing game | massively multiplayer online role-playing game | United Online | Transparent in Your Presence | The Sims Online | Spiegel Online | Playboy Online | online music store |
OPO provides a way to describe the data relative to user's presence in online social systems, for the purposes of data integration and exchange among heterogeneous systems.