When you create a new excel file using HSSF and open it with Excel 2002, excel prompts that the current excel file is saved using an older version and whether the user wants to save it in the older format. I was under the impression that the current version of the API supports excel 2002. The problem becomes more acute in the situation when one is updating (adding rows or changing cell values or format) an existing excel 2002 file.
in 3.0 we need to tell excel what it wants to hear maybe. For users who want the sheet to say "Yes I'm 2000 or XP format" it should.
FWIW: This does not seem to happen in all cases. I tried running org.apache.poi.hssf.usermodel.examples.CreateCells (which produces a simple workbook.xls). I could open the output file in both 2000 and XP (SR-1) without seeing this problem. However, I did notice that POI/HSSF does not put the 'Storage Class ID' into the .xls file when it creates a new workbook from scratch. I thought this might be the cause of the problem, but upon further investigation I discovered that the class ID {00020820-0000-0000-C000-000000000046} is put for all versions of Excel. HSSF just puts in all zeros. Also, there is a BOF record in the workbook, which has a field named 'rversion'. Excel 97 and Excel 2000 put 06100000. Excel XP puts 06200000. HSSF puts 06100000 (same as Excel 97). But that does not seem to make a difference when Excel XP opens the file.
Please try the latest POI-3.5-beta4. I believe the problem is fixed. Both Excel 2003 and 2003 open files generated by POI without warnings. Yegor
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