One of the most controversial and excitingly innovative aspects of Microsoft's forthcoming Windows 8 operating system is its bold, bright Metro interface.
Now the company looks like its killing the Metro name, with Microsoft notifying developers that they should now refrain from using the word Metro, but there's much confusion why. See also Microsoft Windows 8 review.
Has the Paris Metro forced the new type-happy Microsoft user interface underground?
Is it something to do with London's tube-floor-covering newspaper?
See also: Windows 8 release date and features
The likeliest reason is potential litigation by a previous copyright holder.
The German company Metro AG is the prime suspect in the Metro Murder Mystery.
Metro Group, based in Dsseldorf, is one of the world's leading retail and wholesale companies, based on self-service wholesale trade, hypermarkets, consumer electronics stores, department stores and online trade.
Microsoft refuses to comment on whether the Metro muting is related to a trademark dispute.
See also: Windows 8 news, reviews and tutorials
A Microsoft spokesperson told ZDNet that stopping mention of Metro isn't related to any on-going litigation, but wouldn't comment when asked if it related to any kind of copyright dispute that hasn't yet gone to litigation.
"We have used Metro style as a code name during the product development cycle across many of our product lines. As we get closer to launch and transition from industry dialog to a broad consumer dialog we will use our commercial names," said the spokesperson in an apparent denial that Metro was ever going to be the final name for the new user interface.
Microsoft is now advising developers to use "New User Interface" or "Windows 8 style UI" to describe Microsoft's unified design.
In a 2010 Windows Phone 7 "Metro" book Microsoft did explicitly refer to Metro as a code name: "Metro is our code name for our design language. We call it Metro because it's modern and clean. It's fast and in motion. It's about content and typography. And it's entirely typographical."
Metro AG told The Verge that it "does not comment on market rumours," and wouldn't either confirm or deny any potential dispute over the Metro trademark it holds in Germany.
Metro has long been used by Microsoft for its typography-based design language most notably seen with Windows Phone 7 and soon and most radically in Windows 8.
But elements of Metro principles were seen in Microsoft's Zune music UI and as far back as Encarta 95 and Windows Media Center.