Centurion Position in Battle

[Vindex]

... an almost identical likely set of roles. To me that's just obvious.

mile: It's the "likely" that causes me a problem. You are making an assumption based on later models which may, or may not, be parallel and require more evidence than that which we have from the period we are discussing (otherwise, I am not sure we would be discussing it at all!). It is part of the fun of studying and researching.