Notes from an outside-of-the-scene developer:
FS Access Control is all one giant ulong flag. Byte 1 says the application is allowed to access its own data, set it to zero to watch everything break. The last byte means full file permission. The byte before that means it can access debug devices, this would allow (in theory) access to debug gamecards/hardware from retail units. System updates have the 17th and 21st bit set, this may mean that's providing full control for modifying system related files. Some updates just use the full permission bit (last bit).
For the sake of homebrew, we should just ignore this and flag the first bit and the last two bits of the flag. I don't think anything else could possibly matter. Maybe even flagging the first is pointless but I haven't fuzzed this enough to check what breaks. --FrasierCrane (talk) 12:08, 10 May 2018 (CDT)