Two views V1 and V2 are complementary, collaborating views if an element v1 of V1 is formulated in terms of partial information about elements of V2 and V1 adds information to V2 not provided by another view. The partial information in V2 is called join points and provides the range of an insertion mapping. The join points may be spread through V2 effectively crosscutting V2 with information from V1. The domain of the insertion mapping is in V1 and consists of weaves that refer to the join points. The weaves describe enhancements to V2.
Views form a directed graph, called a graph of views.
The view graph must be acyclic. Sometimes we call both views.