Joe Wilcox has a post that has me scratching my head today. In his post Even More on New Office File Formats, he writes

Friday's eWeek story about Microsoft XML-based formats certainly raises some questions about how open they really are. Assuming reporter Pater Galli has his facts straight, Microsoft's formats license "is incompatible with the GNU General Public License and will thus prevent many free and open-source software projects from using the formats." Earlier this month, I raised different concerns about the new formats openness.

To reiterate a point I made a few weeks ago: Microsoft's new Office formats are not XML. The company may call them "Microsoft Office Open XML Fromats," but they are XML-based, which is nowhere the same as being XML or open, as has been widely misreported by many blogsites and news outlets.

There are two points I'd like to make here. The first is that "being GPL compatible" isn't a definition of 'open' that I've ever heard anyone make. It isn't even the definition of Open Source or Free Software (as in speech). Heck, even the GNU website has a long list of Open Source licenses that are incompatible with the GPL. You'll notice that this list includes the original BSD license, the Apache license, the Zope license, and the Mozilla public license. I doubt that EWeek will be writing articles about how Apache and Mozilla are not 'open' because they aren't GPL compatible.

Secondly, it's completely unclear to me what distinction Joe Wilcox is making between being XML and being XML-based. The Microsoft Office Open XML formats are XML formats. They are stored on the hard drive as compressed XML files using standard compression techniques that are widely available on most platforms. Compressing an XML file doesn't change the fact that it is XML. Reading his linked posts doesn't provide any insight into whether this is the distinction Joe Wilcox is making or whether there is another. Anyone have any ideas about this?