Class Libraries & REST APIs for the developers To manipulate & process Files from Word, Excel, PowerPoint, Visio, PDF, CAD & several other categories in Web, DeskTop or Mobile apps. Develop & deploy on Windows, Linux, MacOS & Android platforms....Moreover, this is the limitation in XLS (Excel 97 - 2003) file format...there is no such limitation for XLSX or other advanced MS Excel (2007/2010)...