Windows sleuths have discovered mention of a so-far unannounced new version of Windows 10 inside some of the recent Insider test builds.

Credit: The Walking Cat

This new edition, currently known as "Windows Cloud," is listed alongside other existing Windows 10 editions inside builds as far back as Windows 10 software development kit 15003, as noted by "The Walking Cat" on Twitter. There are listings for both Cloud and CloudN (for the version without Media Player pre-installed, as noted by Brad Sams on Petri.com) inside recent Insider test builds.

So what, exactly, is Windows Cloud? A version of Windows 10 streamed from Azure? Another new Windows 10 subscription plan, in the vein of Windows 10 Enterprise E3/E5? The dreaded (and still nonexistent) Windows 365?

None of the above, my sources say.

Windows 10 Cloud is a simplifed version of Windows 10 that will be able to run only Unified Windows Platform (UWP) apps installed from the Windows Store, my contacts say. Think of it as being similar to the version of Windows 10 formerly known as Windows RT or the Windows 8.1 with Bing SKU.

Windows 10 Cloud is meant to help Microsoft in its ongoing campaign to attempt to thwart Chromebooks with a simpler, safer, cheaper version of Windows 10, my contacts say, though Microsoft is unlikely to position it that way (publicly).

Windows 10 Cloud seemingly has little or nothing to do with the cloud, however, from what my sources are saying I guess the reason Microsoft chose that name is because the company is supposed to be all about "cloud first" these days? Or maybe the Cloud moniker is meant to indicate that this is Microsoft's competitor to Chrome OS/Chromebooks? Or maybe Microsoft intends to claim that Cortana/machine learning in this version makes it a "cloud" OS? Got me....

I reached out to Microsoft to see if the company would share more about Windows 10 Cloud. No word back so far.

Update: "We have nothing to share," said a Microsoft spokesperson.

The Windows 8.1 with Bing edition of Windows -- which was available as an OEM preload only and not for purchase by consumers -- set Bing as the default search engine (though users were allowed to change it). In exchange for that, PC makers got this version of Windows 8.1 for free or a substantially reduced rate from Microsoft.

Windows RT, the version of Windows 10 that powered Surface RT, Surface 2, and third-party ARM-based Windows PCs and tablets, and other devices, could only run a subset of applications built specifically for RT (and not all Universal Windows apps). These apps were available only from the Windows Store and could not be downloaded outside the Store.

Given that references to Windows 10 Cloud are showing up now in Windows 10 Creators Update test builds, I'd guess Microsoft will debut this new edition of Windows 10 on or around April 2017, when sources say the company will begin rolling out the Creators Update to mainstream users.

Here's what Windows 10 Creators Update can do: