What is GPIO4 of RPi is used by RTC HAT(ds1307) for?

I would like to know what is the GPIO4 if Raspberry Pi used for?



Is it used or just blocked?



if it is not used by RTC HAT(ds1307), can I use it for GPIO purpose?

Hi there~



For RTC HAT(ds1307) pin map, please refer to below picture. thanks.