[kingaillas]

I kind of remember a massive CDATA blob... but my memory must be playing tricks on me: Wikipedia shows some sample markup of the pre-2007 Microsoft Office (https://en.wikipedia.org/wiki/Microsoft_Office_XML_formats) and it doesn't look bad at all.

And it seems after 2007 they switched to an ECMA standard.

[ethbr0]

In all fairness, during the first XML migration, I'm sure internal MS folks were just as baffled at the previous format.