an Entity references as follows:
Objectivity/DB is a commercial object database produced by Objectivity, Inc. It allows applications to make standard C++, C#, Java, or Python objects persistent without having to convert the data objects into the rows and columns used by a relational database management system (RDBMS). Objectivity/DB supports the most popular object oriented languages plus SQL/ODBC and XML. It runs on Linux, Macintosh, UNIX and Windows platforms. All of the languages and platforms interoperate, with the Objectivity/DB kernel taking care of compiler and hardware platform differences.