Microsoft is crazy about open-source software lately — with one executive saying recently that an open-source Windows is “definitely possible” — but its newly revealed Edge browser is simply out of the question.

“At this time, we don’t plan to open-source Microsoft Edge or its platform components,” Microsoft declared in a statement in a new FAQ for its Edge browser. “We understand and value the importance about being more open with our roadmap and our core technologies. To that end, we’ve launched Microsoft Edge Platform Status for communicating our roadmap, we’re giving more access to our engineers through social media, and we’re collaborating with the major rendering engine contributors, like Adobe, through a shared source program. We’re committed to being even more transparent with the engineering of Microsoft Edge in the future.”

The statement — which appeared as Microsoft today provided more information about Edge at its Microsoft Edge Web Summit in Mountain View, Calif. — makes things crystal-clear here with regard to open-sourcing the entire browser.

Microsoft employees have talked about this subject before — in monthly Twitter chats, for instance, a Microsoft spokeswoman told VentureBeat in an email today. But it hasn’t been as plainly obvious as it is now.

There has been some speculation about whether Microsoft would go so far as to release and further develop Edge, previously known as Project Spartan, under an open-source license. And Microsoft has spelled out that it didn’t want to adopt WebKit, an open source rendering engine that’s part of Apple’s Safari, with a fork of it running in Google’s Chrome. (Mozilla Firefox, for its part, is already available under an open-source license.)

Today’s statement isn’t a huge shock given Microsoft’s years of preference for internally constructed, proprietary tools. But it’s nonetheless interesting considering the company’s increasing willingness to share core technologies like the .NET software framework under open-source licenses.