I don't do so much with Open XML these days but I still get a few questions from people and I'm still on some of the internal aliases. A recent message from Eric White caught my eye. "Pranav Wagh has built a much improved version of OpenXmlDiff, with a graphical user interface." TBH, I don't think the original "unimproved" version was around when I was messing with Open XML. This would have been a very handy utility to have to hand, especially when my System.IO.Packaging code went slightly awry. If you're working with Open XML, I suggest taking a look with a view to adding it to your "useful utilities" toolbox.