  In this paper, we study the phenomenon that instruction sequences are split
into fragments which somehow produce a joint behaviour. In order to bring this
phenomenon better into the picture, we formalize a simple mechanism by which
several instruction sequence fragments can produce a joint behaviour. We also
show that, even in the case of this simple mechanism, it is a non-trivial
matter to explain by means of a translation into a single instruction sequence
what takes place on execution of a collection of instruction sequence
fragments.
