Musical
definitions - 'N'
Definition: The tune on the top line is referred to as the soprano or treble line, and when you are writing in four parts, this line of music is always written with the stems of the notes pointing upwards. The second line down (written in the treble stave with stems down) is called the alto. The third line (written in the bass stave with stems up) is the tenor. And as you already know, the lowest line is called the bass; when you are writing in harmony, this will always have its stems downwards.
Taken from: Unit 8, p.43