Spreadsheets are a pervasive technology throughout personal and industrial use. Often times, the user is not the author, contributing to a lack of understanding of the purpose and functionality of a spreadsheet. Furthermore, the lack of understanding is a major reason for mistakes in the use and maintenance of spreadsheets.
I present an approach, called explanation sheets, which eases the understanding and maintenance of spreadsheets. I identify the notion of explanation soundness and show that explanation sheets which conform to simple rules of formula convergence provide sound explanations. I also present a practical evaluation of explanation sheets based on samples drawn from widely used spreadsheet corpora and based on a small user study.
In addition to facilitating the understanding of spreadsheets, I describe the process of inferring explanation sheets from a spreadsheet. By means of assessing example spreadsheets, I present a set of inference rules to describe the relationship between a spreadsheet and its explanation.