Usually directed to an inbound aircraft to determine what sort of approach was required. At least, that's what it used to mean!!
Thats correct as there could be many different options for joining instrument approaches or visual circuits, as already stated radar to ILS, or short pattern ILS, PAR, SRA, visual circuit via run and break, over head join with a PFL from high or low key, landing or touch and go, cable up or down and if you where getting a hand over from Lon Mil it was a prenote to ATC, those where the days.