If you have more than 65,536 rows and attempt to save in earlier format,
Excel will give you the following message:
This workbook contains data in cells outside of the row and column limit of
the selected file format. data beyound 256 (IV) columns by 65,536 rows will
not be saved. Formula references to data in this region will return a #REF!
error.

"Carl" wrote:

If I have more than 64K rows in a 2007 spreadsheet (great new feature) ..
what happens to the rows beyond the 2003 limit?