Ionescu's theorem for higher-rank graphs

We will define new constructions similar to the graph systems of correspondences described by Deaconu et al. We will use these to prove a version of Ionescu's theorem for higher-rank graphs. Afterwards, we will examine the properties of these constructions further, and make contact with Yeend's topological k-graphs and the tensor-groupoid-valued product systems of Fowler and Sims.