Nucleus/Core.md

-The `Core` struct holds
+The `Core` struct holds the instances of all attached southbound interfaces as well as the controller's principal network domains. 
 
 ```plantuml
     class Core << (S,Aquamarine) >> {
-        - clients <font color=blue>map</font>[string]interfaces.Client
+        - domains <font color=blue>map</font>[string]interfaces.PrincipalNetworkDomain
+        - sbis <font color=blue>map</font>[string]interfaces.SouthboundInterface
         - database database.Database
         - config controllerConfig