a) You only have been able to do it in the way they want you to: by clicking the File menu and saving as a different type. b) Just because there's an "open" sp

a) You only have been able to do it in the way they want you to: by clicking the File menu and saving as a different type. b) Just because there's an "open" specification, it does not mean their implementation follows it, which is exactly the case for OOXML formats: there are a number of features which Microsoft Office treats differently from what the standard suggests/says, making interoperability/getting things to show up in Office hard as hell. This is coming from someone who has to use the OOXML SDK daily.