This VBScript example uses the Write event and warns the user that the item is about to be saved and will overwrite any existing item and, depending on the user's response, either allows the operation to continue or stops it.
Function Item_Write()
myMsg = "The item is about to be saved. Do you wish to overwrite the existing item?"
myResult = MsgBox(myMsg, 289, "Save")
If myResult = 1 Then
Item_Write = True
Else
Item_Write = False
End If
End Function