An extended relational data base management system for engineering design

At present, the use of the relational model in the engineering design support domain is restricted due to the following: lack of ability to handle complex objects, no support for Abstract Data Types, inappropriate concurrency control for long transactions, no support for versioning and update propagation, poor efficiency, and insufficient design rule checking and consistency contraints enforcement. A simple relational database management system is designed and implemented under the UNIX operating system to incorporate two major extensions: support of user-defined Abstract Data Types and operators, and built-in Design Data Versioning. The design, implementation, and possible extensions to these new facilities are described