Custom Format Interferes With Itself

I have a custom format that is applied to column AU. Here is the worksheet code which is placed in the worksheet code area:

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Count > 1 Then Exit Sub
If Target.Column <> 47 Then Exit Sub
If Target.Value = "" Then Exit Sub
On Error Goto Errhndl
Application.EnableEvents = False
Target.Value = "Map " & UCase(Left(Target.Value, 4)) & " <" & UCase(Mid(Target.Value, 5, 2)) & "-" & Right(Target.Value, 2) & ">"
Application.EnableEvents = True
Exit Sub

Errhndl:
Application.EnableEvents = True

End Sub


It works well on the sheet, if I remember to only put three numbers, three letters and then two more numbers (allwithout any spaces. Lowewr case ok). (eg. 122rmm25 is then transformed into Map 122R <MM-25>). On the sheet this works. Coming off of the UserForm, it tries to apply this format to text already formated and messes up royally!!!

Is there any way to either reverse this proccess coming off the UserForm or to stop the worksheet from appling this format to the value of the cell in question if the source is in the wrong format to be changed? How do I detect what format the text is in? (Raw, formatted correctly or over formatted)