Epistemological aspects of object schemes

There is an increasing demand for database management systems to support nontraditional applications, such as computer aided design (CAD) and decision support systems (DSSs), which deal with complex objects. Complex objects are objects that have nonatomic components (unlike the traditional relational model). Many researchers have designed object systems to support complex objects. Five levels of scheme representations are identified: (1) record-structure level (lowest), (2) relational level, (3) logical level, (4) semantic level, and (5) object level (highest). Different object schemes proposed in the literature differ in their levels of representation. The authors discuss the need for a formalism for the object level of representation and describe a formalism for an object scheme called NEXUS