Unlike the case for distinct UDTs, the system does not create a default cast for a newly created structured UDT. The exceptions to this are the Period and Geospatial data types, which are Teradata internal structured UDTs, and their default casts are predefined.
You can optionally create casts to support any conversions you need to support the structured UDT.
You are not required to create explicit casting functionality for a structured UDT; however, you must create a cast if the structured UDT is to perform in certain SQL expressions such as the USING request modifier, or to participate in various loading operations such as Fastload and MultiLoad.
To determine if a structured type has casts defined for it, use the HELP TYPE statement (see HELP TYPE).