According to a report at GameSpot sister site ZDnet, Microsoft is planning to release its next wave of operating systems--codenamed Threshold--in spring 2015. Sources confirmed to reporter Mary J. Foley that Microsoft executive vice president Terry Myerson used the name "Threshold" in an internal email recently.

If plans hold, Threshold will feature updates to Microsoft's three main operating systems platforms--Xbox One, Windows, and Windows Phone--allowing them to share common elements more easily than in the past. A single app store for all three platforms is also in the pipeline, the report claims.

These platforms already share a common Windows RT core, but Microsoft is reportedly planning to unify the developer toolset for all three of the platforms. What's more, sources told ZDnet that Threshold will support the same main set of "high value activities" across platforms.

These include expression/documents (Office), decision making/task completion (Bing), IT management (Intune), and something labeled "serious fun." Before Threshold arrives, however, Microsoft is reportedly planning further updates to Windows 8 and Windows Phone to be released in 2014.

Outgoing Microsoft CEO Steve Ballmer mentioned "high value activities" in July as part of the announcement of a company-wide reorganization. It was also here that Ballmer laid out his vision for "One Microsoft" focused around unifying the company's products and services.

The Threshold codename is taken from the Halo series. It is the name of the planet around which the first halo ring orbited in the original Halo: Combat Evolved. Microsoft's Siri competitor will reportedly be called Cortana, also associated with the Halo franchise.