Microsoft’s upcoming Windows 8 operating system has reached Release To Manufacturing (RTM) status, and it further has ditched the Metro UI name. Instead, the company has decided to use the term “Windows 8-style UI” to refer to the new interface and applications.

While the actual tile-based interface itself is still part of the OS, several factors seem to have caused Microsoft to rebrand it. A Microsoft representative was quoted by ZDNet in stating that Metro UI was simply an internal code name never intended to be used as the final brand name. Specifically:

“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.”

That’s all well and good–the company has used many codenames for in-development products in the past. However, it does seem to be a bit late in the game to announce that the Metro UI name is suddenly dead, especially considering the public development cycle with two public betas so far and numerous articles using the Metro name to refer to the new Windows 8 interface and apps.

Another possible reason for the change to “Windows 8-style UI” lies in alleged legal threats by German retailer Metro AG. According to The Verge, sources have indicated that Microsoft backed off from using the Metro name in order to avoid a legal dispute with the retailer. As far as trademarks go, Microsoft could have fought them in court with a chance of being allowed to continue using Metro as the companies and the products referred to by their “Metro” brand names are in different industries. Metro AG is a huge company, however. It would have the money and resources to give Microsoft a good court battle for the name.

In an interesting move, it seems that Microsoft and Metro AG have backed away from a court battle by agreeing to disagree. The Verge quotes an internal Microsoft memo as stating that due to talks with “an important European partner,” (possibly Metro AG) the company is discontinuing its usage of the Metro term/brand. Until a more permanent and official brand name is released, Microsoft has decided to go with “Windows 8-style UI,” and is instructing everyone else to as well.

Whatever the real reason for the change, the Metro UI is gone, at least in name. Will you miss the Metro term?