Microsoft has already challenged the Apple App trademark in the U.S., asking the U.S. Patent and Trademark Office to refuse the iPhone maker's registration request on the basis that it's a generic name, not something to which Apple can lay exclusive claim.
Apple has equated the right to claim "App Store" as similar to Microsoft's own defense of one of Microsoft's most valuable trademarks -- Windows -- which Apple has said also is a generic name.
Now Microsoft has taken the fight to Europe to challenge Apple's obtained rights to the trademarks "App Store" and "Appstore" in the European market.
On Thursday, Microsoft joined HTC, Nokia and Sony Ericsson in filing filed formal applications for declaration of invalidity in the Community Trade Mark office, the office that oversees trademarks in the Euro Zone.
Microsoft and the other companies want to invalidate Apple's trademark registration, "claiming the trademarks should not have been granted because they lack distinctiveness," according to a Microsoft spokesman.
Here is a statement from Microsoft:
Microsoft and other leading technology companies are seeking to invalidate Apple's trademark registration for APP STORE and APPSTORE because we believe that they should not have been granted because they both lack distinctiveness. The undisputed facts establish that "app store" means exactly what it says, a store offering apps, and is generic for the services that the registrations cover.