The ACT module handles NNID accounts.
ACT service "act:a"
ACT service "act:u"
|Command Header||Available since system-version||Description|
|0x00010084||Initialize? cmd = u32 ctrsdkversion_probably, cmd = unknown, cmd = 0x20(kernel PID header), cmd = PID value written by kernel, cmd = 0x0(handle-transfer header for kernel), cmd = handle value.|
This is the service used by regular applications.
Trusted Root CAs
Even though ACT-sysmodule uses ptm:s, it doesn't use CheckNew3DS at all. It's unknown how this sysmodule determines whether to use "CTR"/"KTR" for a request-header value for HTTPS requests.