Abstract: A compiler is provided to a network element management subsystem for compiling rules and behaviors of device types into nested meta data structures of model databases. The rules and behaviors of the device types are specified via definitions describing controls of the device types, and features assignable to the device types. In one embodiment, the compiler is a two phase compiler comprising a parsing and list building phase and a database building phase. The device type model databases are loaded into memory to allow fast access and traversal. Each of the model databases comprises a plurality of nested meta data structures. Data are conditionally retrieved by selectively traversing the model databases using navigation sequences. An array of evaluation functions is further provided to evaluate predicates embedded in the nested meta data structures in view of operational data. During operation, user and system actions are interpreted through device emulation accessing the appropriate model databases.