Please note that one character often takes on more than one of these roles on a raid. If everybody targets through the Main Tank, the Main Tank is also Main Assist. If the Main Assist takes over when the Main Tank dies, the Main Assist is also Secondary Tank. The in-game Looking for Group window describes 8 roles, Primary + Secondary Tank, Primary + Secondary Healer, Melee + Ranged Damage, Crowd Control, and Combat Support.