The .xlr file extension relates to spreadsheets created by Microsoft Works suite. Microsoft Works provided a less expensive and more simplistic spreadsheet program than Microsoft Excel. Often bundled with new PCs, the suite of products was discontinued in 2008. The file type was particularly unpopular due to a lack of compatability with other programs, including Microsoft Excel.
An .xlr file allows rows and columns to be defined in a file within Microsoft Works. Other features commonly found in other spreadsheet applications are also found in .wks files including formulas, charts and graphs. Although Excel 2003 supports .wks files, Excel 2007 does not support them.
Microsoft Excel is a commercial spreadsheet application written and distributed by Microsoft for Microsoft Windows and Mac OS X. Pre-2007 versions of Excel use XLS as the primary format for saving files. It features calculation, graphing tools, pivot tables, and a macro programming language called Visual Basic for Applications. It has been a very widely applied spreadsheet for these platforms, especially since version 5 in 1993, and it has almost completely replaced Lotus 1-2-3 as the industry standard for spreadsheets. Excel forms part of Microsoft Office. The current versions are 2010 for Microsoft Windows and 2011 for Mac OS X.
Microsoft Excel up until 2007 version used a proprietary binary file format called Binary Interchange File Format (BIFF) as its primary format. Used as the basis for XLS files it is a persistence format that supports authoring and manipulating content in workbooks and workbook templates. Most versions of Microsoft Excel can read CSV, DBF, SYLK, DIF, and other legacy formats.