Sofware development benefits from an engineering approarh, because it has the same needs for keeping track of enhancements, modifications and standards. The progressive upgrading of software involves three factors: configuration control, host/satellite development, and development standards and methodologies. Configuration control is applied to developments that are useful additions to the kernel software, and permits variant projects to proceed in parallel with independence of bug fixing. Features of parallel development projects can also be merged into a single future system, which may yield a net saving of 50% in development activity. Formal review is a key control over quality in the enhancement of packages, and involves the whole project team. The engineering approach has been of benefit in relation to development costs, and also in the degree of customer support that can now be given.