The third argument of the SetCertificateProperty and SetCertificateExtension methods is a constant representing the data type of the property or extension. Four data types are supported - String (VT_STRING), Long (VT_LONG), Time (VT_DATE), and Binary (VT_BINARY). String is used to specify a string value which is to be encoded as a Unicode string. Long is used to specify an integer value. Time is used to specify a ChoiceOfTime value. Binary is used to specify any type of data not covered by the other three types. This includes complex or custom certificate extensions which are encoded using extension handlers.