It looks like Apple is getting ready to rebrand one of its biggest products

We've got another big indicator that Apple is preparing to rebrand OS X, its desktop operating system.

There have been rumours and speculation for years that Apple is going to drop the "OS X" brand.

It's a relic of the Cupertino company's pre-mobile past, and its other operating systems all follow a different format: productOS.

The Apple Watch runs watchOS, for example, while the iPhone and iPad runs iOS, and the Apple TV has tvOS.

OS X, which runs by default on all Macs, MacBooks, and Mac Pros, is expected to turn into "MacOS" - and new documentation from Apple very strongly suggests that will happen.

As 9to5Mac spotted, the company has published information about Earth Day 2016, a big environmental initiative this year. But the tech blog noticed that it referred to its desktop operating system as "MacOS," rather than "OS X."

And interestingly, the website has since been updated to remove the reference to MacOS - suggesting it was an accidental inclusion.

Developers have also previously found references to "MacOS" in OS X's code - suggesting that the name change is coming soon.