The present document is part 2 of the Stage 3 specification for an Application Programming Interface (API) for Open Service Access (OSA). The OSA specifications define an architecture that enables application developers to make use of network functionality through an open standardised interface@ i.e. the OSA APIs. The present document specifies the Common Data Definitions of the OSA. The Common Data Definitions contain data-types that are common across the rest of the OSA API. All aspects of the Common Data are defined here@ these being: ? Data Definitions. ? IDL Description of the data types. ? WSDL Description of the data types. ? Reference to the Java? API description of the data types.