Handling Constraints and their Exceptions: An Attached Constraint Handler for Object-Oriented CAD Databases.

Alejandro P. Buchmann R. S. Carrera M. A. Vazquez-Galindo Handling Constraints and their Exceptions: An Attached Constraint Handler for Object-Oriented CAD Databases. 65-86 1991 On Object-Oriented Database System db/books/collections/dittrichDB91.html#BuchmannCV91