I have no idea if it is or not... it seems the norm is to do 3 A levels, yes? In scotland we usually do 4 or 5 highers... they tried for a while to compare the two using UCAS points, but it failed miserably! I think most uni courses will say you need 3 A levels or 4 highers... so i'm guessing that's as equivalent as you get.
standard grades as also apparently the same as gcses.... we do 7 standard grades... actually, i think its 8 now... the whole thing has changed in the last couple of years so who knows whats going on now.