The other way of phrasing that line is: to garentee that you can display any Word document, you need to be able to support any formatting that Word supports. P

The other way of phrasing that line is: to garentee that you can display any Word document, you need to be able to support any formatting that Word supports. Parsing a Word document is much simpler than displaying a Word document, often people mean the latter when they say "open a Word document".