IEC 61970-301:2013 defines the Common Information Model (CIM), that is an abstract model representing all the major objects in an electric utility enterprise typically involved in utility operations. By providing a standard way of representing power system resources as object classes and attributes, along with their relationships, the CIM facilitates the integration of Energy Management System (EMS) applications developed independently by different vendors, between entire EMS systems developed independently, or between an EMS system and other systems concerned with different aspects of power system operations, such as generation or distribution management. SCADA is modeled to the extent necessary to support power system simulation and inter-control center communication. The CIM facilitates integration by defining a common language (i.e. semantics) based on the CIM to enable these applications or systems to access public data and exchange information independent of how such information is represented internally. Major changes from the fourth edition include the following: - transformer models have been modified to be consistent for use by distribution and transmission purposes; - a more general and clear naming approach was added and several ambiguous attributes related to naming were dropped; - phase component wires models have been enhanced to describe internal phase specific attributes and connections; - addition of diagram layout models to facilitate the exchange of diagram layout information.