I was initially confused about these regs and still am somewhat but as mentioned it applies to all wiring systems that are contained within the shell of the space be it a room or corridor etc that is simple to understand. This will include all direct clip, all containment systems and their fixings.
The question is whether it does or doesn't apply to cabling above plasterboard, given that standard plasterboard would only probably resist for about 15/20 mins then premature failure of your wiring systems is easily predictable, the whole reason why we introduce these fire resistance install methods is to protect those going into a building like the fire brigade are not going to get caught up do to premature failure the fixing systems of the cabling, if the cable is run on a void side of a standard plasterboard ceiling then one needs to be considerate of the cable runs and/or how they are fixed. If you have clipped a run of cable along the side of the joist itself above standard plasterboard then I would suggest a fire rated clip still and longer screws than normally required, this then means the cable will remain as long as the joist is in position which is a damn site longer than if plastic clips were used.
Noted these are my opinions based on info I can gather, I am currently doing a renovation but it has 1hr fireboard throughout so I am more relaxed about this approach but still do consider runs more carefully to get me into the habit.
Edit -
PS I will add that cables drilled through joints are going to survive the duration of the joists survival so can be ignored, its just long cable runs on the side of joists above standard plasterboard I was raising issue with.