The Soil Retaining Wall spreadsheet is developed and maintained in the ODS Open Document Spreadsheet format with LibreOffice. Only this and the similar OpenOffice and derivatives of this presently support all features. To download LibreOffice or the similar OpenOffice for all platforms, see http://www.libreoffice.org http://www.openoffice.org Mac users may find it works with NeoOffice: http://www.neooffice.org/neojava/en/ Gnumeric will run the calculation but not display included images: https://projects.gnome.org/gnumeric/ The same applies to online programs such as Google Drive, which also requires registration. Microsoft Office prior to 2013 will display the spreadsheet but not actually calculate anything. Excel 2013 should run the calculations. XLS/XLSX files made by any of the new programs should run in the older Excel versions. Please send me comments or improvements. Theo Schmidt