Distinct data types
When you create a distinct data type, the database server automatically registers explicit casts from the distinct data type to the source data type and from the source data type to the distinct data type. You must create casts on distinct types to handle conversions between the new distinct data type and other data types in the database or use explicit casts in your SQL statements.
For more information and examples that show how you can create and use casts for distinct types, refer to the topics on casting in the HCL OneDB™ Database Design and Implementation Guide.