Hilchos Gitten, Kav Hanaki

Hilchos Gitten, Kav Hanaki, Lubavitcher posek
wrote sefer Shaar HaKolel, birur of Baal Hatanya's sidduer of Nusach Ari, calls it that because Arizal says there are 12 gates into Jerus. one for each gate, but a 13th gate for BTs and people who don't know what shevet they are from