> I find neither naming scheme optimal. The best I've come up with is to use > a placeholder character instead (like "xax", "_ax", or "$ax"), but that > isn't that beautiful either. So, either way is fine by me. Can't we use union trick (with some padding love) to represent all of them at once : lower 16bits ax, lower 32bits eax and full 64bits rax? Just my .00002 cents, as I'm clearly not an assembly guy. Bye, Philippe.