Dynamo/React selfweight application

Hi, Attached is a definition for a parametric truss, for running in React Structures. When considering generating loadcases, the GetModelSelfWeight and ModelSelfWeight nodes, how are these used to apply a load to the structural model? Are they applicable to applying loads as: nodes, members and panels. All advice and guidance appreciated. Oh!!! Loadcase.CaseName and Loadcase.CaseType do these nodes with the same input, variables and output are both necessary?? regards Kenyon dynamo_truss_Rev_B