''' <summary>Auslesen eines zeichen-markierten Teilstrings</summary>
''' <param name="Text">zu durchsuchender Text</param>
''' <param name="StartMarker">Zeichen: danach beginnt Teilstring</param>
''' <param name="EndMarker">Zeichen: davor endet Teilstring</param>
''' <param name="StartIndex">null-basierter Startindex der Suche</param>
''' <returns>zeichen-markierter Teilstring (oder Leerstring)</returns>
Private Function ExtractSubstring(ByVal Text As String, _
                       ByVal StartMarker As Char, ByVal EndMarker As Char,
                       ByVal StartIndex As Integer) As String
 
     If String.IsNullOrWhiteSpace(Text) Then Return String.Empty
     If StartIndex < 0 Then StartIndex = 0
 
     Dim startposition As Integer = Text.IndexOf(StartMarker, StartIndex)
     If startposition < 0 Then Return String.Empty
     startposition += 1
     Dim EndMarkerPosition As Integer = Text.IndexOf(EndMarker, startposition)
     If EndMarkerPosition < startposition + 1 Then Return String.Empty
 
     Dim subtext As String = _
     Text.Substring(startposition, EndMarkerPosition - startposition)
 
     Dim lie As Integer = subtext.LastIndexOf(StartMarker)
     If lie >= 0 Then
        subtext = subtext.Substring(lie + 1)
     End If
     Return subtext
End Function