Microsoft Excel 2010Compatibility mode tool per Microsoft's Website
"New features in Excel 2010 are disabled when you are opening previous versions of Excel in Excel 2010. For example, new 2010 Sparklines and Slicers features are disabled with opening earlier version of Excel. Workbooks created in the Excel 97-2003 file format (.xls) automatically open in compatibility mode. Workbooks created in Excel 2010, but destined for people who use earlier versions of Excel, should turn on compatibility mode to prevent accidental use of functions and features that are incompatible with the earlier versions of Excel. This is very important for users who plan to share workbooks with other users who have not yet migrated to Office Excel 2007 or a later version."
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