Structured extension of COBOL for handling data bases

The most important aspects of a modest data base management system are described on the basis of our experiences in implementing it. Data structuring facilities of the system include two basic data structures: lists and binary search trees; and a simple rule of their top-down composition. The class of structures that may be obtained this way is rather restricted in comparison with the CODASYL proposal, but still fairly powerfull and permits definition and easy implementation of an elegant data manipulation language (DML). Operations of the DML have simple syntax and semantics and allow implementation in which the structure of the data base is protected against illegal actions on the part of the programmer. Since implementation of the system requires some modest effort, we offer it as an experiment which shows how existing software facilities can be extended in simple and still essential ways, for applications where all the generality of general data base management systems is not really necessary. Design of the system was motivated by the work of Schneidermann and Scheuerman on structured data structures and it contains several important clarifications and improvements of their suggestions, together with implementation aspects.