It’s been a while, but I’m pretty sure I used to have macros that differentiated between shift, lshift, and rshift. When I tried the following macro, however, I cast at my mouseover target regardless of which shift key I was pressing. The macro behaved this way even with all of my add-ons turned off. Are these modifiers no longer used?
/cast [mod:rshift,@mouseover]Flame Shock; [nomod]Flame Shock