The warning now appears in , in a section labeled "Naming your app."

"Make sure your app name doesn't include the word metro," Microsoft cautioned. "Apps with a name that includes the word metro will fail certification and won't be listed in the Windows Store."

The ban on "metro" was first reported by the blog Tuesday.

Microsoft's move was the latest in its deprecation of the Metro label, one it had associated with Windows 8 for nearly a year, and used much longer with other products, including Zune and Windows Phone.

Last week, , but claimed that it had used it only as a code name. That held little water, however; The company had never said as much regarding Windows 8 or Windows RT, and in presentations, press releases and developer documents, the firm had repeatedly used the word to describe the apps and the WinRT-based environment they run in.