I would like to create an XLS file on our main frame. I am using the Excel 97 Developer's kit with the Biffviewer and also a hex editor for research. The documentation covers the biff records nicely but when I look at an XLS file with a hex editor, the biff codes (bytes) are within some other undocumented bytes. (i.e. the first byte is not the BOF (09h), in fact it is quite far away.) Also, the last few bytes in the file are not 0A 00 00 00. What do these surrounding bytes represent and how do I know how to create them?