Jet fragmentation of multiparton configurations in a string framework

We study the fragmentation of arbitrary parton configurations, with particular emphasis on events where two partons have a small invariant mass. Within the framework of string fragmentation, a natural transition is obtained between two nearby partons (qg or gg) and a single parton (q or g) carrying the full momentum (provided that colours match), i.e. the final state hadrons are distributed in the same way in both cases. An explicit model for the fragmentation process is formulated, based on and extending the present Lund model, and some consequences are discussed.