  In this paper, we discuss the problem of the software engineering of a class
of business spreadsheet models. A methodology for structured software
development is proposed, which is based on structured analysis of data,
represented as Jackson diagrams. It is shown that this analysis allows a
straightforward modularisation, and that individual modules may be represented
with indentation in the block-structured form of structured programs. The
benefits of structured format are discussed, in terms of comprehensibility,
ease of maintenance, and reduction in errors. The capability of the methodology
to provide a modular overview in the model is described, and examples are
given. The potential for a reverse-engineering tool, to transform existing
spreadsheet models is discussed.
