These are the NFC services for New 3DS.
A total of 6 sessions can be open simultaneously for all of these services combined.
NFC service "nfc:u"
This is the main NFC service. This was first seen in the Super Smash Bros eShop demo(only in the exheader, the demo doesn't actually use it), at that time no system-module was available for NFC on CDN. The New3DS module for this was added with 8.1.0-0_New3DS.