User-Defined types (UDTs) allow users to create custom data types that model the structure
and behavior of data in their applications. UDTs can augment the Teradata Database
with data types having capabilities not offered by Teradata predefined (built-in)
data types. UDTs are defined with the CREATE TYPE statement.
Teradata Database supports three types of UDTs: distinct, structured, and array.
A distinct UDT is based on a single predefined data type such as INTEGER or VARCHAR,
and so on. It is basically a redefinition of an already predefined SQL data type.
A structured UDT is a collection of fields called attributes, each of which is defined
as a predefined data type or other UDT (which allows nesting).
An array UDT is a collection of values, of the same data type, having a specific lower
and upper bound. The bounds can define a single dimension or multiple dimensions.
For more information, see “Additional Information on UDTs and UDFs” on page 75.