Public Function ReadBlocks _
        (ByVal filename As String) As List(Of List(Of String))
 
        If Not IO.File.Exists(filename) Then Return Nothing
 
        Dim lines() As String = IO.File.ReadAllLines(filename)
        If lines.Length < 3 Then Return Nothing
 
        Dim startindex As Integer = -1
        Dim blocklist As New List(Of List(Of String))
        Dim blockheader As String = ""
 
        For i As Integer = 0 To lines.Count - 1
 
            If lines(i).Trim.ToUpper.EndsWith("_START") Then
                If Not startindex = -1 Then Return Nothing 'ENDE fehlt
                startindex = i + 1
                blockheader = lines(i).Trim.ToUpper.Replace("_START", "")
            End If
 
            If lines(i).Trim.ToUpper.EndsWith("_ENDE") Then
                If startindex = -1 Then Return Nothing 'START fehlt
                Dim block As New List(Of String)
                block.Add(blockheader)
 
                For k As Integer = startindex To i - 1
                    block.Add(lines(k))
                Next k
 
                startindex = -1 'Suche nach dem nächsten Block
                blocklist.Add(block)
            End If
        Next i
 
        If Not startindex = -1 Then Return Nothing 'ENDE fehlt
        Return blocklist
    End Function