I am looking into a new project which involves adding XML structure to a Word document using Custom XML but I don't know how the i4i case affects this.
1) Microsoft recommends using custom controls in the document. Can this validate using an XML Schema file? It looks to me more like a way to create a template and not really for adding tags to existing content.
2) The i4i judgement about Custom XML only concerned North America. Did Microsoft remove the feature worldwide or can I still access it in Australia?
On 2), technically it would be legal, but MS did not consider it worth the additional effort, and nor would I.
There are alternative approaches and which I covered in my blog Windward Wrocks (links and better formatting at my blog):