What are "important wake timers" in Windows 10?

SiXandSeven8ths' answer is for wake timers in general, not important wake timers.

I've quoted below the best answer that I could find that specifically describes "important wake timers". It was provided by one of the moderators of the Microsoft answers community. It turns out that he does not work for Microsoft, however, no one in the discussion thread there could find a more in-depth answer coming directly from Microsoft.

"Important wake timers are a new class of wake timer that includes things like reboots after a windows update that requires one. They supersede all other settings and can only be prevented if the computer is off or if the timer is disabled in task scheduler"

Source: ZigZag3143, from the following link: http://answers.microsoft.com/en-us/insider/forum/insider_wintp-insider_perf/important-wake-timers-only/1847ce44-d293-4c89-87fd-30b1ad0fd0a1

I found this:

https://answers.microsoft.com/en-us/insider/forum/insider_wintp-insider_perf/important-wake-timers-only/1847ce44-d293-4c89-87fd-30b1ad0fd0a1?auth=1

One answer says:

It's the ability for your PC to be brought out of sleep at a specific time. Say for example you wanted to back up your system at 1am every day but didn't want to leave your machine on all night - the wake timer would wake your PC up ready for the scheduled backup to take place. The power management options you have set may then allow it to go back to sleep until you're ready to use the PC again.