Where is CMOS battery

I can not find CMOS battery.
Does Aerobook Plus have CMOS battery?

No, the laptop does not have a CMOS battery. The laptop primarily uses NVRAM.

BIOS settings is erased when the battery is zero.
If my aerobook plus is not connected by USB-C cable,
BIOS settings is gone. The time data seems reset,too.
What does it mean? My aerobook plus does not have NVRAM?

NVRAM is in the bios chip, some minor settings such as time and boot order are in CMOS memory.

If the battery is zero, boot order and time will be lost.
Is it a specification?
How are the time and boot order in CMOS saved without battery?

The built-in battery works as a CMOS battery, if the battery is discharged below normal and is blocked by the controller, then the settings stored in the CMOS will be reset.

Thank you so much for your lucid explanations.
I understood your reply.