The hold point markings are exactly as have been described above.

When taxiing out to the runway, the pilot would be unaware whether the ILS was currently being used for Cat I or Cat II/III approaches (but they would have a pretty good guess based on the weather!). But you can be sure that ATC would know. Therefore, the taxiing pilot would be cleared to proceed as far as the relevant holding point for the runway. For example, the Cat I hold could be designated "Alpha 1"; the cat II as "Alpha II".