I've always understood that the drive in straps (punched sections of the rails/plates) were for temporary use until the final location was determined; then it was intended to be secured by nails or screws. That's why there are multiple holes in those plates.
The only ones that don;t require additional fastening are the cans (Juno?) with the nail pre-attached at the factory.
IMHO I don't care for roofing nails. While they're handy (big head, short length), I had an issue with them once. I ran out of 1 1/4" DW screws, so I grabbed a few roofing nails from a can on the site.
I'll be damned if more than half of the heads didn't pop off before we were done at the site two weeks later.
As I went through re-fastening the boxes I'd mounted, I wound up swearing off roofing nails as a result.
That said, I don't think it's a Code violation per se, as the Code doesn't specify fastening means, it only specifies the distance the fastener can protrude into the interior of the box IIRC.
Of course, there's the inspector who failed a buddy for not using wood screws to mount the various boxes throughout the job (he used 1 1/4" DW's); the inspector fell back on "I'm the AHJ" when he couldn't produce an actual Code ref.
ETA - It seems the Halo lights use a stronger metal for their nails than the stuff used for roofing nails.
[This message has been edited by DougW (edited 11-10-2006).]
