what is m1 coach in train

M1 coach is a type of coach in Indian Railways that belongs to the AC Three Tier Economy Class. In train AC THREE TIER ECONOMY coaches are denoted by M1, M2, M3, and so on. M1 is an AC three tier economy coach, where M stands for AC 3 TIER ECONOMY COACH and 1 stands for FIRST. Therefore, M1 means AC THREE TIER ECONOMY FIRST COACH. The layout and interior of the M1 coach can be found in various YouTube videos.