By default, Vantage performs implicit type conversion on a UDT argument that has an implicit cast that casts between the UDT and a predefined character type.
To define an implicit cast for a UDT, use the CREATE CAST statement and specify the AS ASSIGNMENT clause.
Implicit type conversion of UDTs for system operators and functions, including CHAR2HEXINT, is a Teradata extension to the ANSI SQL standard.