excel File Format

A key consideration is file compatibility. Excel 97 through Excel 2003 all use the same file format,
so file compatibility isn’t a problem for these four versions. Microsoft introduced a new file format
with Excel 2007, and it’s also used in Excel 2010. Fortunately, Microsoft has made a compatibility
pack available for Excel XP and Excel 2003. This compatibility pack enables these older versions
of Excel to read and write the new file format.
It’s important to understand the difference between file compatibility and feature compatibility.
For example, even though the compatibility pack enables Excel 2003 to open files created by
Excel 2010, it can’t handle features that were introduced in later versions.