A Data Definition and Mapping Language.

A data definition language is a declarative computer language for specifying data structures. Most data definition languages concentrate on the declaration of logical data structures with little concern for how these structures are physically realized on a computer system. However, the need for data definition languages which describe both the logical and physical aspects of data is increasingly apparent. Such languages will be a key element in the translation of data between computer systems, as well as in advanced data management systems and distributed data bases. This paper reviews past work in the data definition language for describing both logical and physical aspects of data. Applications of these "generalized" data definition languages are also discussed. [ABSTRACT FROM AUTHOR]