| Subject | English | Italian |
| gen. | model of open regionalism | modello di regionalismo aperto |
| comp., MS | open content model | modello di contenuto aperto (A set of XML document rules that states that an element in an XML document can have additional child elements and attributes that are not declared in the schema that the document references) |
| astr. | open model | universo aperto |
| stat. | open model | modello aperto |
| comp., MS | Open Systems Interconnection model | Open Systems Interconnection (A networking model introduced by the International Organization for Standardization (ISO) to promote multi-vendor interoperability. OSI is a seven-layered conceptual model consisting of the application, presentation, session, transport, network, data-link, and physical layers) |
| commun., comp. | open systems interconnection reference model | modello di riferimento ISO/OSI |
| commun., comp. | open systems interconnection reference model | modello OSI |