keithl
That's it precisely. Imagine an old triangular airfield, now running with a main instrument runway east-west and two visual only cross runways. If only the main has IAP's, but you wish to land on one of the cross runways (due cross wind etc), you may shoot the approach to the main and if visual at or above the aerodromes VMC/circling minima, position (circle) visually to the cross runway. The next logical step is for considerate airport owners to provide an IAP for the cross runways that terminates at the same aerodrome VMC/circling minima, but also positions you roughly in line with the runway for the visual approach. I think I know what I mean, if not how to explain it!!