<Li> validate the structures by overlapping the models </Li> <Li> discovering discrepancies, gaps, lineage, metrics at data structure level . </Li> <P> Each database management system (DBMS) and database tools have their own language for the metadata components within . Database applications already have their own repositories or registries that are expected to provide all of the necessary functionality to access the data stored within . Vendors do not want other companies to be capable of easily migrating data away from their products and into competitors products, so they are proprietary with the way they handle metadata . CASE tools, DBMS dictionaries, ETL tools, data cleansing tools, OLAP tools, and data mining tools all handle and store metadata differently . Only a metadata repository can be designed to store the metadata components from all of these tools . </P> <P> Metadata repositories should store metadata in four classifications: ownership, descriptive characteristics, rules and policies, and physical characteristics . Ownership, showing the data owner and the application owner . The descriptive characteristics, define the names, types and lengths, and definitions describing business data or business processes . Rules and policies, will define security, data cleanliness, timelines for data, and relationships . Physical characteristics define the origin or source, and physical location . Like building a logical data model for creating a database, a logical meta model can help identify the metadata requirements for business data . The metadata repository will be centralized, decentralized, or distributed . A centralized design means that there is one database for the metadata repository that stores metadata for all applications business wide . A centralized metadata repository has the same advantages and disadvantages of a centralized database . Easier to manage because all the data is in one database, but the disadvantage is that bottlenecks may occur . </P>

What stores metadata instead of actual data in dbms