A file with .xl extension is an Excel Spreadsheet file, similar to XLS, that stores data in rows and columns. It was an earlier file format that is no more supported by Excel now. Data stored in XL files could be exported to other formats such as CSV. These could also be converted to PDF using the Excel’s default Save As method. XL files could be opened with Microsoft Excel only.
XL File Format
XL files are saved as binary files and their internal file format specifications are not documented anywhere. However, the general binary file format for XLS File Format Specifications file format may also be considered if someone tries to write a piece of code to reverse engineer these files.