A little while ago I predicted how I thought Apple would number versions of macOS from Big Sur onwards. I was wrong, and apologise for having been misleading. With macOS version 11.1 now undergoing beta-testing, Apple has made it very clear how it is numbering versions after the long reign of Mac OS X.

Over the next year, we will see macOS 11.0 to 11.x, where x is probably (by tradition) going to be around 6 or 7. Then in the autumn/fall of 2021, expect to see Apple release the next major version, macOS 12, which should in turn follow a similar cycle through 12.0 to 12.x.

Rather than have Supplemental Updates, this enables Apple to release minor patches using the third number, as it did with macOS 11.0.1, as needed.

For many, this is a great improvement, although as usual nothing comes for free. Software which remains capable of running in versions of macOS before 11.0 needs to cope with its different numbering system. It also means that, like some apps such as Firefox, if Apple keeps on an annual major release cycle, it will ascend major version numbers more rapidly than it ever has before: in ten years time, we’ll probably all be complaining about the problems we’re having with macOS 21.0.

If you need to convert the old and new systems into a monotonically increasing numeric series, this means that you can take the ‘minor’ version number for macOS 10 up to 15, and for versions above the major version number of 10, simply add 5 to that. For example, that makes Mojave 14, and Big Sur’s successor 17.

What we will discover next in macOS 11.1 is whether Apple has also incremented its backward-compatible version numbering from 10.16.0 to 10.16.1, or left it alone for those scripts and older code which are blissfully unaware of this major change.

Now, if you’ll pass me the hat, I think I have a job to do.