Microsoft’s Internet Explorer development team has confirmed there will be a browser extension system for Project Spartan, meaning developers will be able to extend its functionality with software that can be built directly into the browser.

“Yes. We’re working on a plan for extensions to a future update to ‘Project Spartan,’ the developer relations team for IE said during a QA chat on Twitter Tuesday.

The news is significant since it indicates some type of a developer ecosystem will evolve around the browser, allowing functions to be added that are not supported natively. Such extensions could allow tabs to be given specific color codes, or allow bookmarks to be catalogued in new ways, or Web pages to be archived locally.

Google Chrome and Mozilla Firefox have their own systems for adding functionality to those browsers. The Microsoft developers didn’t say if the Spartan extensions will be available through the Windows 10 Store, which is being remodeled for the new OS.

The team also eliminated any doubt that Spartan will become the default Windows 10 browser. “IE will be available for Windows 10 and can [be] enabled by the user,” they said in one tweet.