## 1 Introduction  
With the introduction of the smart grid concept, electrical power utilities operate a large number of systems (or applications in a system) in both transmission and distribution domains. For the efficient operation of the systems, it is expected that the need for data exchanges between the systems will be increased significantly. For example, data exchange between a transmission system operator (TSO) and a distribution system operator (DSO) has been newly required for auxiliary service procurement and balancing purposes [1, 2]. Therefore, the complexity of mappings required for the interface between systems will also rise exponentially since conventional one-to-one data mapping by agreement between individual system managers should be conducted for the data exchange. Due to a lack of a standard data exchange process, a system exchanges the same data in multiple formats, and any change in the data format results in failures of data exchange. Under the smart grid environment with frequent exchange of a large amount of data, a standard semantic model is required to solve the associated interoperability problems by enabling seamless data exchange [3, 4, 5, 6, 7]. International electrotechnical commission (IEC) common information model (CIM) is an abstract model to express power system networks and resources, and it is defined in IEC 61970 [8] and IEC 61968 [9] for transmission and distribution system objects, respectively. CIM is maintained by unified modeling language (UML) as it represents power system resources in the form of object-oriented classes, attributes, and associations between the classes [10]. CIM provides a powerful and flexible system integration technology with the help of agreement over the semantics of data being exchanged [11; 12]. Due to the availability of a consensus standard data model, CIM has been adopted by many electrical utilities to enable the standard data exchange process, thereby accomplishing the interoperability requirements for the smart grid. The California independent system operator (CAISO) takes advantage of CIM to ensure an integrated environment of multiple systems and applications [13; 14] and the European network of transmission system operators (ENTSO-E) developed a common grid model exchange specification (CGMES) based on CIM for network model exchanges to ensure interoperability between TSOs [15]. In addition, Chinese electrical power control centers (CEPCCs) have adopted CIM to exchange data between an automated voltage control system to the existing energy management system (EMS) and integrate multiple control centers through a constituted hierarchical network [16]. Some challenges regarding the problem of identifiers have been reported in applying the CIM framework as a standard integration process [16; 17]. Master resource identifications (mRIDs), specified in IEC 61970-301 [8], are recommended to be used as persistent and globally unique identifiers in CIM-based data exchanges. The CIM concept of modeling authority sets (MASs) was introduced in [18] and has been applied to multiple CIM-based integration projects for the assembly and merging of power system network models [17; 19; 20]. Although the uniqueness of identifiers for power system resources can be achieved by the introduction of Universally Unique Identifier (UUID) and MAS concepts, the problems of boundary sets containing all boundary points necessary for a merge model remain, which requires the mapping of different mRIDs for the same power system resource to ensure that the objects with different mRIDs are confirmed to be identical. Previously, only a few mapping boundary sets were required by mutual agreement since an mRID for a power system resource is issued by a regionally divided MAS and only a few elements are in the boundary regions. It means that only a few local ID mappings are required, and it can be manually performed.