The term Center is usually used to describe the main member in a single's senbatsu. The 'center' gets center position in the formation of the members. The term is also used for centers from B-Sides and stage songs.
The 'center' format is not always used in singles, so the center could be shared between two people - known as a WCenter (Double Center) or the single could have no center and fairly distribute the position between different members.
The list below features all songs with a center. Solo songs and duets aren't include.