Public Function IsValidDate(ByVal Year As UShort, ByVal Month As Byte, ByVal Day As Byte) As Boolean
 ' Determine whether the given date exists in the current Gregorian calendar
 ' Example: IsValidDate(2006, 11, 30) = True, IsValidDate(2006, 11, 31) = False
 '
 ' Visustin sample algorithm
 ' ©2006 Aivosto Oy (www.aivosto.com)

 If Month >= 1 And Month <= 12 Then
  If Day >= 1 Then
   ' Compare to maximum days in this month
   If Day <= DaysInMonth(Year, Month) Then
    Return True  ' Valid date
   Else
    Return False ' Day exceeds max days in month
   End If
  Else
   Return False ' Day cannot be below 1
  End If
 Else
  Return False ' Invalid month
 End If
End Function