#include <IndexedConstituentUserInfo.h>
IndexedConstituentUserInfo is an implementation of IConstituentUserInfo, i.e. it provides means to attach a particle, label and vertex to a fastjet pseudojet.
The particle is held by pointer, the label by index (along with a pointer to the label index to dedcode it), and the vertex is missing. The index 0 corresponds to no label and negative values indicate the constituent is a ghost, i.e. has very low energy and so has little effect on the jet four vector.