Devon is writing the following code to avoid what?

Devon is writing the following code to avoid what?
<script language=”vb” runat=”server”>
Sub Application_BeginRequest(Sender as object, E as EventArgs)
If (Request.Path.Indexof(chr(92)) >= 0 OR _
System.IO.Path.GetFullPath
(Request.PhysicalPath) <> Request.PhysicalPath)
then
Throw New HttpException(404, “Not Found”
End If
End Sub
</script>

A.
Type safety

B.
GET source code path