When invoking a scalar or aggregate UDF that is defined with a TD_ANYTYPE result parameter, you can use the RETURNS data type or RETURNS STYLE column expression clauses to specify the desired return type. The column expression can be any valid table or view column reference, and the return data type is determined based on the type of the column. You must enclose the UDF invocation in parenthesis if you use the RETURNS or RETURNS STYLE clauses.
For detailed information, see Defining Functions that Use the TD_ANYTYPE Type.