Office 2011 for Mac: Save Excel Workbooks in Old File Formats
Excel for Mac 2011 lets you save a workbook in the following old Excel formats if you’re creating a spreadsheet for or with someone who has a version of Excel prior to Excel 2007:
Excel 2004 XML Spreadsheet (.xml): Excel 2004 and Excel 2008 can use this XML format. This was a precursor to the open source standard XML format that is now Excel's default.
Excel 97-2004 Workbook (.xls): Save in a format that was used by these old versions of Excel.
Excel 97-2004 Template (.xlt): Save a template in a format that was used by these old versions of Excel.
Excel 97-2004 Add-In (.xla): Save a macro-enabled workbook as an Excel add-in for these old versions of Excel. Excel 2008 can't run macros or add-ins.
Excel 5.0/95 Workbook (.xls): Save in a format that was used by these old versions of Excel.
These old formats are worth trying when sharing files with people using programs that are ostensibly "compatible" with Excel.
Saving in these old formats will cause data loss with worksheets larger than 65,536 rows or 256 columns. Many objects will turn into pictures and not be editable. Expect compatibility problems with pivot tables, tables, graphs, charts, conditional formatting, protection, collaboration, and other Excel features that have been significantly upgraded. Old formats are not recommended for everyday use.