The data catalog is the interface between data users and data providers. In order to make it easier to find data in data catalogs, it is necessary to unify metadata for registered data to enhance and improve its quality. Therefore, we have developed the “SIP Data Catalog Item Specification and its Explanation Guideline,” which standardizes data catalog items in different formats. Based on the DCAT specification, which is an international standard for data catalog items, the usage conditions and connector control items are included from the viewpoint of data distribution.