Using Excel 2003 & Excel 2002 we update a spreadsheet saved in XML format so
it can be read by another application. But when we re-save the file in XML it
does not update some of the document properties including the LastSaved
field. The spreadsheet has multiple tabs.

When saved by Excel 2003 today 29th July 2008 10:19 Aust EST:
<DocumentProperties xmlns="urn:schemas-microsoft-com:office:office"
<Author(name)</Author
<LastAuthor(name)</LastAuthor
<LastPrinted2008-07-22T05:44:04Z</LastPrinted
<Created2008-02-25T04:37:03Z</Created
<LastSaved2008-07-22T02:25:48Z</LastSaved
<Company(name)</Company
<Version11.9999</Version
</DocumentProperties

I edited the file with Wordpad to change Author & LastAuthor then made a
change using Excel 2002 and saved it again and the Authors and dates had not
changed (but version was updated to account for using Excel 2002).

Do these fields only get updated under certain circumstances?