There are several groups: (1) The Amitābha group, also styled 淨土三部, is 無量壽經, 觀無量壽經 and 阿彌陀經. (2) The Vairocana group is 大日經, 金剛頂經 and 蘇悉地經; also called 三部祕經. (3) The Lotus group is the 無量義經, 妙法蓮華經 and 觀普賢菩薩行法經. (4) The Maitreya group is 觀彌勒菩薩上生兜率天經, 彌勒下生經 and 彌勒大成佛經.