I think we need to get some clarity with terminology, which is
definitely confusing when it comes to Excel formats.
The .xlsx format used by default in modern versions of Excel *IS*
OpenXML. (It's called "Open" because it's an open standard.)
If you are talking about the XML which is generated by older (before
2007) versions of Excel, that is *not* OpenXML. That is most properly
just called Excel XML. It is sometimes referred to as "XML
And if all that isn't enough, OpenOffice.org had its own XML format as
well, which is not the same as either of the above Excel formats.
Understandably, a lot of people think of OpenOffice (formerly
StarOffice, way back when) when they see "OpenXML".
So, if you want to be sure you're on the same page with someone else,
I strongly recommend avoiding the term "OpenXML". When you said "2003
XML" (meaning XML emitted by Excel 2003), I thought that was not a bad
choice of terminology. For that format, you need to mention the 2003,
because without specifying an Excel version, many people will just
assume you mean .xlsx.