Where is the i2c bus on the GIPIO ports?

Hi,
Trying to connect ds1307 rtc module to CB1+PI4B
The overlays dtb file says that they are on the pins i2c0 "PI6", "PI7", i2c3 "PH4", "PH5".
i2c1 pins are missing.
Where are these pins on the board?

Start with the DTB overlay mentioned in the issue and the CB1+PI4B board pin mapping. Compare the listed i2c0 and i2c3 pins with the board's available GPIO ports, then document where i2c1 is exposed or clarify its absence. Done means the i2c1 pins can be identified unambiguously for connecting the DS1307 module.

Written by the indexing model from the issue text.