A system file should have the System Attribute flag set. This can be detected using the following function
 

Private Function IsSystemFolder(folderName As String) As Boolean
 If d.Length < 4 Then Return False
 ' root directory reports as hidden and system
 Dim di As New IO.DirectoryInfo(d)
 If (di.Attributes And IO.FileAttributes.System) <> 0 Then Return True
 Return False
End Function
  

 
If we are interested in System Folders, we may also need to know if it is a hidden folder
 

Private Function IsHiddenFolder(folderName As String) As Boolean
 If d.Length < 4 Then Return False
 ' root directory reports as hidden and system
 Dim di As New IO.DirectoryInfo(d)
 If (di.Attributes And IO.FileAttributes.Hidden) <> 0 Then Return True
 Return False
End Function
  

 
When identifying System and Hidden Folders, we may wish to detect certain strings in the folder path because they could indicate the folder contents should not be edited.

Private Function IsSimilarToSystem(d As String) As Boolean
 If d.Length < 4 Then Return False ' root directory reports as hidden and system
 If d.Contains("\winsxs\", StringComparison.CurrentCultureIgnoreCase) Then Return True
 If d.Contains("$"c) OrElse d.Contains("~"c) Then Return True
 Dim di As New IO.DirectoryInfo(d)
 If (di.Attributes And IO.FileAttributes.System) <> 0 Then Return True
 If (di.Attributes And IO.FileAttributes.Hidden) <> 0 Then Return True
 Return False
End Function
  

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