What happens to NULL strings in tracing code?
By default, the tracing components in this version of the Windows Driver Kit (WDK) search for NULL strings in the arguments that you pass in functions. As a result, you do not have to verify each argument to prevent NULL strings from causing an exception.
In earlier versions of the WDK, the WPP_CHECK_FOR_NULL_STRING macro performed this function. If you build your kernel-mode driver or user-mode application by using this version of the WDK, you can remove the macro from your source code.