# Blockchain Implementation Method for Interoperability between CBDCs
## 3 The Proposed Method  
### CBDC Management Method Based on ISO/IEC 11179  
The ISO/IEC 11179 metadata registry is an international standard for data interoperability. Interoperability is a property in which systems can be used interchangeably with other systems of the same or heterogeneous type. Data interoperability can be understood and exchanged without any additional work by other systems or repositories. A computer does not know when to distinguish between specific data with equivocal meanings. For example, when the word \"Apple\" is given to a computer, the computer does not distinguish between \"Apple\" as in the fruit and the Apple Corporation. As the data for representing other data, metadata is used to distinguish the meaning of data, and the metadata structure the means for interpretation of the data. Metadata expression languages include Resource Description Framework (RDF) [18] and Web Ontology Language (OWL) [19]. The ISO/IEC 11179 Metadata Registry (MDR) is a metamodel that manages metadata through registration and authentication of metadata [20]. The MDR supports data element creation, registration, and management to share information between systems; it structurally supports the sharing, expression, and identification of the meaning of data and can involve data interoperability using the data stored. We manage the CBDC to the data elements of the MDR. An efficient exchange of CBDCs should ensure that the sender and receiver interpret the same CBDC information. CBDC information sharing requires the expression of a standardized CBDC structure. Central banks will build CBDCs with their technology and guarantee its transaction. In this section, we discuss how to exchange and receive transactions between CBDCs. MDR can finely express the data and represent it to the Concept layer and Representation Layer. This may involve representing such data value as the range of the domain. In other words, we can identify the data in semantic form using the MDR. While the integrity of data stored in the blockchain is difficult to maintain, as in a database, MDR can help ensure the integrity of the CBDC. The MDR manages data using data elements. Figure 1 presents an overview of the metadata registry. The data elements of the MDR represent the data as the Concept layer and Presentation layer. The concept layer expresses data and domain information with the Data Element Concept and Conceptual Domain. The Representation layer implies a data element and value domain that expresses the data value format and measurement units. The MDR can obtain the conceptual classification of data and expression information for data values. The \"*\" and \"1\" of the Data Element are the relationships of each element. A single Value Domain can relate to many Data Elements. Figure 2 shows the data element structure. Data elements are represented by Object Class, Property, and Representation. Object classes provide a structure for representing objects in data and represent concepts that contain data. For example, the object class of the Korea CDBC is Digital Currency. Property is a common feature that can distinguish object classes. For example, the Bank for International Settlements (BIS) distinguishes the digital currency as a CBDC, Non-CBDC Token, and Non-CBDC Account. The Data Element is expressed as a combination of value domain, data type, and unit of measurement. Figure 3 is a CBDC example of the data element concept; it can express an object class as digital currency and property as a central bank. The data value of the MDR is expressed using a conceptual domain and a value domain. Figure 4 shows the relationship between the Conceptual Domain and the Value Domain. The MDR expresses the data in the descriptive or enumerated form. The descriptive form expresses the data values in the Described Conceptual Domain and Described Value Domain. The enumerated form expresses the meaning of the data in the Enumerated Conceptual Domain, Value meaning, Permissible value, and Enumerated Value Domain.