The purpose and scope of metadata in MDM varies, and some common types are structural, semantic, quality, and governance. Structural metadata describes the schema, format, and structure of the master data entities and attributes, such as their names, types, lengths, formats, and constraints. This helps to validate and transform the master data from different sources and to ensure its consistency and compatibility. Semantic metadata describes the meaning, context, and business logic of the master data entities and attributes, such as their definitions, descriptions, synonyms, aliases, and rules. Quality metadata describes the quality, completeness, and reliability of the master data entities and attributes like their values, ranges, frequencies, errors, and anomalies. Governance metadata describes the ownership, accountability, and control of the master data entities and attributes such as their owners, stewards, domains, policies, and processes. All these types of metadata help to understand and interpret the master data; assess and improve it; manage and monitor it; as well as ensure its relevance; accuracy; integrity; validity; security; compliance; consistency; compatibility; etc.