  We use a spectator framework to investigate the spectral properties of
quark-quark-gluon correlators and use this to study gluonic pole matrix
elements. Such matrix elements appear in principle both for distribution
functions such as the Sivers function and fragmentation functions such as the
Collins function. We find that the contribution of the gluonic pole matrix
element in fragmentation functions vanishes. This outcome is important in the
study of universality for fragmentation functions.
