The character set of a UDF is determined by the character set of the user that creates the function. Therefore, if the user creating a UDF has a character set of LATIN, the UDF has a character set of LATIN. If the user creating a UDF has a character set of UNICODE, the UDF has a character set of UNICODE. FNC_GetQueryBandValue assumes the input character parameters are in the function character set and returns the output parameters in the same character set.