Public Function Rot13(ByRef Text As String) As String
  Dim i As Long  
  Rot13 = Text
  For i = 1 To Len(Text)
    Select Case UCase$(Mid$(Text, i, 1))
    Case "A" To "M"
      Mid$(Rot13, i) = Chr$(Asc(Mid$(Text, i, 1)) + 13)
    Case "N" To "Z"
      Mid$(Rot13, i) = Chr$(Asc(Mid$(Text, i, 1)) - 13)
    End Select
  Next i
End Function

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