Do you know, is it a bug of Office 2010?
Yes, it is a bug. I have reported it to Microsoft.
And as I see, you have changed some part in the 'document.xml' file...Can we change the xml file by ourselves,
Yes, if you know what to do. It isn't difficult. I have no definitive information - all I know is based on experience, but what appears to be the case is that a basic structure that should look like this:
<mc:AlternateContent>
<mc:Choice>
<m:oMath>
Part (possibly all) of an equation, followed by the
Second part (possibly none) of the equation
</m:oMath>
</mc:Choice>
<mc:Fallback>
A picture of the equation
</mc:Fallback>
</mc:AlternateContent>
... ends up looking like this, instead:
<mc:AlternateContent>
<mc:Choice>
<m:oMath>
Part (possibly all) of an equation, followed by the
</mc:Choice>
<mc:Fallback>
A picture of the equation
</mc:Fallback>
</mc:AlternateContent>
Second part (possibly none) of the equation
</m:oMath>
and you have to put it back together properly so that Word can open it. You have to use a tool that is not a 'consumer' of xml because consumers (including Word) are not allowed to do anything with broken files except report the error(s); it's a bit of a
catch-22 situation: Word breaks the file and is not allowed to mend it!
is there a reference documentation that explain xml structure?
Yes - it's about 6000 pages long. Google for either ECMA 376 or ISO 29500 - versions of the standard from two different standardisation bodies (the differences are inconsequential in most circumstances).
Enjoy,
Tony
www.WordArticles.com