Rear number plate light trim working loose ...

[spenno]

Hi all, I am trying to find a few special bolts for my micra's rear number plate light trim. It's something I see on this model a lot just driving round ... the trim has been working its way loose and after opening the boot, removing the plastic screws and looking inside there are a handful of odd bolts I've not seen before with what I guess are their matching nuts missing. Anyone know what these are called, I keep searching but it's not easy finding them as I don't know what they're properly called. Thanks.