Recent advances in computer hardware have not been matched by comparable advances in computer software, inhibiting the production of reliable software at greater levels of productivity. Development of software is restricted by the so-called "maintenance backlog". Productivity in the maintenance sector has not kept pace with increasing annual labour costs, making the maintenance of software the major item in the budget, of organisations responsible for the development and maintenance of software. Gains in productivity can be anticipated by the exploitation of software-maintenance tools, within the framework of an Integrated .Software Maintenance Support Environment (ISMSE). for which a high-level design has been proposed in this thesis, offering comprehensive support for all phases of the software life-cycle, particularly the maintenance phase. A key factor in the reliable modification of software is the time taken to gain the prerequisite understanding, by a study of the system's documentation. This documentation degrades over a period of time, becoming unreliable, inhibiting maintenance of the software, which may be a large capital asset, ultimately, the software may become impossible to maintain, requiring replacement. Understanding gained during maintenance is wide-ranging and at various levels of abstraction, but is often NOT well-recorded, since no effective documentation system exists for recording the maintenance history of large software systems. The documentation paradigm in this thesis, used within the framework of an ISMSE, aims to provide a means of recording the knowledge gained during maintenance, facilitating easier future maintenance, and preserving the reliability of the documentation, so reducing the time required to gain an understanding of the software being maintained. This provides a powerful means of increasing productivity, while simultaneously preserving a valuable capital asset
