DB2 UDB and Sybase data sources allow you to define your own data types that map to the data types for your data source. When the DataServer reads the schema information for a user-defined data type, it reads the data-source base data type and maps it to the equivalent OpenEdge data type. Suppose, for example, that you create a data type named phone_number and map it to the char data type. In the schema holder, the DataServer represents your phone_number data type as a CHARACTER data type. If you make any changes to a user-defined data type, you must update the schema holder to reflect those changes.