title: Apache POI 3.12 compatibility with both excel 2003 and 2013
body: <p>I am trying to use apache poi 3.12 to generate excel sheets . I have used XSSFWorkbook and other corresponding classes to create the excel sheet however I am saving it with xls extension which is giving some errors while opening the generated excel sheet. I am aware of the fact that the so generated excel should be saved with xlsx as I am using XSSFWorkbook . The main problem is that the generated excel should be compatible with excel 2003 aswell how do I generate excel file that is compatible with excel 2003 , 2007 and 2013? </p>