Solo - relational function

Solo ` a single or dominant voice `

The soloist (whether accompanied or not) determines the musical direction, and if accompanied, others provide some support of that direction. A Solo, however, need not be extensive in group situations. The function of Solo can, and often does, shift rapidly among players, sometimes so rapidly that a single line may appear to be shared among two, three or more players.

source: Nunn (1998) Wisdom of The Impulse. On the Nature of Musical Free Improvisation. pdf part 1 page 26 of 50 url link 1 [1]

source: Nunn (1998) quoted & discussed in Free Ensemble Improvisation, Harald Stenström, page 90 url link 1 [2] link 2 [3]