Public Class SpecialComparer
    Implements IComparer(Of String)
 
    Public Function Compare(x As String, y As String) As Integer _
        Implements System.Collections.Generic.IComparer(Of String).Compare
 
        x = x.Replace(".", "")
        y = y.Replace(".", "")
 
        Dim xp() As String = x.Split(" "c)
        Dim yp() As String = y.Split(" "c)
 
        If xp(0) > yp(0) Then Return 1
        If xp(0) < yp(0) Then Return -1
 
        If xp.Length = 1 And yp.Length = 1 Then
            Return 0
        ElseIf xp.Length = 1 And yp.Length > 1 Then
            Return -1
        ElseIf xp.Length > 1 And yp.Length = 1 Then
            Return 1
        End If
 
        Try
            If CDec(xp(1)) > CDec(yp(1)) Then Return 1
            If CDec(xp(1)) < CDec(yp(1)) Then Return -1
        Catch ex As Exception
            Throw New ArgumentException("Invalid Sort-Arg / numeric")
        End Try
 
        If xp.Length = 2 And yp.Length = 2 Then
            Return 0
        ElseIf xp.Length = 2 And yp.Length > 2 Then
            Return -1
        ElseIf xp.Length > 2 And yp.Length = 2 Then
            Return 1
        End If
 
        Return String.Compare(xp(2), yp(2))
 
    End Function
End Class

  Dim str() As String = {"AAA", "Block", "Block 1", "Block 10", "Block 10.1", _
                               "Block 10.1 aa", "Block 10.1 ab", "Block 10.1", _
                               "Block 10.2", _
                               "Block 2", "Block 3", "Block 10.10", "CCC 1", _
                               "CCC 10", "CCC 2"}
 
  Array.Sort(str, New SpecialComparer)