A WYSIWYC (what you see is what you compute) spreadsheet

Sheet based programming languages (spreadsheet applications) are one of the most popular classes of applications on personal computers. Unfortunately, many spreadsheets created by both inexperienced and experienced users are incorrect. A fundamental reason for this is the independence of the computational structure of a spreadsheet from its visible structure. We define a new sheet-based visual language which attempts to overcome this difficulty by using the visible structure of the spreadsheet as the means of specifying the computational structure-a What You See is What You Compute (WYSIWYC) spreadsheet