Mmmm.. lets see, over the last 10 years I have spent nearly a million dollars on XML/Java application development, so maybe, just maybe I know something about this.
I participated in the eBXML project until it became lost in international bureaucratic vacation taking rather than doing anything of import. And I can assure you that nothing, nothing associated with XML or XML tags is patentable because its like patenting a combination of words on a page, no way to do this to create a novel invention. XML is an international standard that defines the XML code layer and the DTD and DLD layers that manage the definition of the XML and call resources associated with these tags. Its like discovering PHP on the web one day and deciding to develop PHP pages and then deciding to patent using it to write a web page that includes a flash movie... its stupid, thats what PHP was designed to do, what is the unique invention?
XML is simply a carrier, just the same as HTML. The difference being is that I can use it to call resources and pass them data.
XML is server side because Browsers are not written to read it, but XML could be sent to any proprietary rendering engine that is designed to accept XML tags and interpret them. Any Web Browser could serve as such a proprietary engine if the definitions were shared via a plug-in or some such.
In the case of Word, it is acting as a non-browser, non-server rendering engine with a specific set of XML tags of meaning that resolves into Markup Instructions as well as resource calls.
There is no difference between this action and my Java based programs that accept the XML we write and generate HTML that Web Browsers recognize.
In my opinion using XML to carry date is bizarre. But then if people like to do things the hard way, I think they should. XML is much better at describing text than carrying data.
You don't invent HTML tags. You do invent XML tags. And then you have to write a parser for your tags. i4i claims they invented a new way to parse and index the tags of a markup language. I am not claiming that I agree with their claim. Nor have I said anything about the merit of their case. And yes, I do understand that you do not agree with their claim.