XLR, Microsoft Works spreadsheet or chart (.xlr)
The XLR Spreadsheet file format
Spreadsheets created by the Microsoft Works Suite are saved as XLR files. The spreadsheet creation program under the Microsoft Works Suite offered a cheaper alternative to the Microsoft Excel (contained in Microsoft Office) series. The lack of compatibility between much of the Microsoft Works Suite (including XLR files) upset users and the Works line became discontinued in 2008. File conversion is possible to allow users to still use old XLR files, but other programs and file types with greater levels of cross-compatibility have taken over.
Technical details of XLR files
Much like other spreadsheet programs (e.g. Microsoft Excel), XLR files allow rows and column definition as well as formula insertion and usage, charts, graphs, and more. While the Microsoft Works suite offers many useful functions, it is limited in abilities compared to the Office suite. This leaves the XLR files and other Microsoft Works files for more personal use instead of professional use or distribution. Businesses may not find these programs and file useful, but those not needing many functions outside of basic charts, math, and graphs find it more than enough to get things accomplished.