RCM6600W: What's PE4 used for?

PE4 is used for some mysterious purpose on the RCM6600W. It’s also hard wired to external interrupt 0 (I0CR). If I need to set I0CR to priority 2, is that going to mess with anything that the RCM6600W is doing with PE4? I’m hoping PE4 is just being used as GPIO and it’s a moot point, but I want to make sure I have my bases covered.

I don’t believe PE4 is used on the RCM6600W. When I checked the schematic, it was shown as not connected.

Looking through other MiniCore modules, I see that the RCM5700 uses it to reset the Ethernet PHY. The RCM5600W uses it to drive an input on the SRAM. The schematics for both the RCM6600W and RCM6700 show it as not connected.

Where were you seeing it used?