IEC TR 62351-12:2016(E) discusses cyber security recommendations and engineering/operational strategies for improving the resilience of power systems with interconnected Distributed Energy Resources (DER) systems. It covers the resilience requirements for the many different stakeholders of these dispersed cyber-physical generation and storage devices, with the goal of enhancing the safety, reliability, power quality, and other operational aspects of power systems, particularly those with high penetrations of DER systems. It addresses the resilience issues for cyber-physical DER systems interconnected with the power grid, building on the concepts and the hierarchical architecture described in the Smart Grid Interoperability Panel (SGIP) draft DRGS Subgroup B White Paper – Categorizing Use Cases in Hierarchical DER Systems.