what is prep rank in jee advanced? is in normal rank or something else?

Prep rank doesnt mean a rank in JEE Advanced. Youre not alloted a rank in JEE Advanced Rank List.The vacant seats reserved for SC, ST and PwD candidates, which dont get filled in the counselling will be allotted to the candidates of respective categories for admission to a preparatory course.Preparatory courses mean that for one year you will be prepared and trained in IIT, and then after one year youll be declared pass or fail according to which you will get a direct admission in an undergraduate course from next academic session