Search notes:

Registry: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU

AU stands for Automatic Update.

AUOptions

1 Keep my computer up to date is disabled in Automatic Updates.
2 Notify of download and installation.
3 Automatically download and notify of installation.
4 Automatically download and scheduled installation.

NoAutoUpdate

A value of 0 indicates that automatic updates are enabled. 1 disables automatic updates.
The default is 0

ScheduledInstallDay

Indicates the day on which an update is scheduled. 1 = Sunday, 7 = Saturday, 0 = every day.

UseWUServer

Setting UseWUServer to 1 causes Automatic Updates to use a server that is running Software Update Services instead of Windows Update.

Don't reboot while someone is logged on

Apparently, setting the value NoAutoRebootWithLoggedOnUsers to 1 prevents Windows Update from rebooting while someone is logged on: 
@reg add "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" /v NoAutoRebootWithLoggedOnUsers /t REG_DWORD /d 1 /f
Github repository about-Windows-Registry, path: /HKEY_LOCAL_MACHINE/SOFTWARE/Policies/Microsoft/Windows/WindowsUpdate/AU/dont-reboote-while-someone-is-logged-on.bat

See also

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate

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