A two-dimensional spreadsheet could fairly readily be implemented by extending the existing support for linked spreadsheets. A subclass of LinkedSpreadsheet, TwoDSpreadsheet, whose contents were more easily edited could hold a spreadsheet of spreadsheets - a two-dimensional spreadsheet. To access an element of a two-dimensional spreadsheet, one must have two indices. The first index would be implementable as the index of a cell in a TwoDSpreadsheet. The second index would then be the index of a cell in the spreadsheet that that first index cell linked to. For example, 2dCell x: 2 y: 3 would return the third cell of the second linked spreadsheet in the two-dimensional spreadsheet. Summing and averaging the spreadsheets would be a logical extension of the existing linked spreadsheet code that accomplishes that.