You are tracking 200 to pass overhead an airfield. The airfield has an NDB and a localiser. The localiser final approach course is also 200. What should you use for tracking guidance, for the final 20nm? The answer of course is the LOC, regardless of what navaid you've been using up until now. I got that one right! It is of course entirely inappropriate for the enroute waypoint context, but it's in the AIP regardless.
Interesting - what if you capture a LOC side lobe?
UTR