"It is one case to walk through 7000 pages of rather technical
documentation and to try to extract something useful out of it for
a concrete question. It is another thing to look at the actual XML
produced by the Microsoft Office 2007 suite.
"There we have the workbook as main entry-point for spreadsheets
aka for what MS Excel flushes out. Such a workbook does contain
normally general informations about the sheets, file-revision and
so on. Now we know that something that may become ISO standard is
at least vendor and application independent to be used by more then
those who pushed for that standard, right? And hey, it's all XML
(except things like the binary Printer-driver embedded in each
OOX-document). So, it's open, right...?"