Regarding ISO485: https://docs.m5stack.com/en/unit/iso485

In ISO485 terminals it shows ground instead of shield as the third terminal as here https://static-cdn.m5stack.com/resource/docs/products/unit/iso485/iso485_04.webp and here: https://static-cdn.m5stack.com/resource/docs/products/unit/iso485/iso485_02.webp

But in the schematics it shows that terminal as shield: https://static-cdn.m5stack.com/resource/docs/products/unit/iso485/iso485_sch_01.webp

I guess it makes sense it is GND since it is RS485 requirements.

So what is the GND terminal really connected to? Is it connected to the GND of RS485 side or the the point shown as shield in schematics(where there is an RC parallel filter)?