The LSO Reference Architecture characterizes the management and control domains and functional management entities that enable cooperative LSO capabilities. The architecture also identifies the Management Interface Reference Points, the logical points of interaction between specific functional management entities. These Management Interface Reference Points are further defined by Interface Profiles and implemented by APIs. The High Level LSO Reference Architecture is shown in Figure 2. Note that this is a functional architecture that does not describe how the functional management entities are implemented (e.g., single vs. multiple instances), but rather identifies functional management entities that provide logical functionality as well as the points of interaction among them.