In the past, you had to hand in a post before you could learn from the teacher. Posts are generally scarlet, folded, and the words "learning from teachers" are written on the surface. In the post, it was written that disciple XXX wanted to learn from the teacher, his date of birth, address of his native place, and some even wrote his vows and aspirations. An affidavit is also called a disciple's post, written or written evidence. Also called disciple post, it means that if you write a teacher post, you will write a written evidence to the master, which means that you will vote in the name of the master from now on.