Diocletian: legions and rank structure

[Wolf_of_Romulus]

I've got a few questions about the late 3rd century. I understand resources are limited, but any help would be greatly appreciated. First. are there any good resources where I can see the ranks of the roman legions during the reign of Diocletian? I've got a great book on the roman army by Adrian Goldsworthy and he talks about the equestrian ranks that began to replace the senatorial ones, but I'm looking for more of the junior command. After he talks about the different tribunes, prefects, and praepositii, he says "Apart from their titles, even less is known about the various more junior ranks attested in the later army." I want to know what those various, more junior ranks are, or at least what they are called. What I'm really looking for is a top to bottom list of ranks, and a brief description of their responsibilities (if such information is even available). Thanks in advance for any help.