Cast distinct data types

A distinct type inherits none of the built-in casts of the built-in type that a distinct type might use as its source type. Consequently, the built-in casts that exist to implicitly convert a built-in data type to other data types are unavailable to the distinct type that uses the built-in type as its source type. However, when you create a distinct type on a built-in type, the database server provides two explicit casts to handle conversions from the distinct type to the built-in type and from the built-in type to the distinct type.