Abstract: A method for automating the production of worksheet files of the type used by electronic spreadsheet programs. The spreadsheet program has an associated filed format specification that defines the format in which the spreadsheet program stores and receives data in a worksheet file. The spreadsheet program is capable of processing the worksheet files to produce an output spreadsheet. The method of the invention comprises receiving pattern data specifying positions for one or more variable data items to appear on the output spreadsheet, receiving variable data specifying the variable data items, and merging the pattern and variable data to produce merge data specifying the variable data items and their positions. The merged data is then output into the worksheet filed in said format, such that the spreadsheet program can then use the worksheet file to produce the output spreadsheet having the variable data items at the specified positions.