Public Function AddDateTimeSpan(ByVal timespan As dateTimeSpan) As DateTime
  Property Description  
    Method Name AddDateTimeSpan  
    Argument - timespan DateTimeSpan value to add  
    Returns The new date time with the time added on  
    Description Creates a new DateTime containing this DateTime + DateTimeSpan value  
    Remarks The addition is done in compliance with the W3C XML rules for date times and durations (these rules are somewhat convoluted!)