I'm trying to figure out if the reforms talked about on http://the-orb.net/textbooks/nelson/late_roman_empire.html were for both halves. Diocletian ruled the eastern half, but it seems the reforms affected both halves. The only thing I've found that might help answer this was from Wikipedia: "In terms of regional jurisdiction there was no precise division between the four tetrarchs, and this period did not see the Roman state actually split up into four distinct sub-empires." However, this is not clear to me whether this means the emperor in the West could just order people in the East around.
Thank you.
Just to point out, the link you included doesn't work, so it's impossible to see what specific reforms you are discussing. That said, the short answer is yes, the administrative reforms initiated by Diocletian applied to the entirety of the Empire. It is best to conceptualize the Tetrarchy (as well as previous and future splittings of imperial power) as the creation of spheres of influence, rather than separate political entities. While Diocletian and Maximian were the locus of authority in their respective spheres, they both shared imperial power, and their actions were valid throughout the Empire. It's also worth remembering that Diocletian was always the senior Augustus, even if Maximian was his nominal equal. It was his ability to influence (and if necessary, command) his supposed colleague that arguably allowed the Tetrarchy to function.