Rank Structure in an alien culture ?

Been thinking about rank structure for the Flight, the minitary arm of the Rim Coalition<br />This thread was a discussion from earlier about it: http://www.starfrontiers.us/node/4544<br /><br />and since Jacobsar has been doing really cool stuff working on the UPF rank structure with artwork to match I was thinking about the Flight, partly also because I need to get off my can and wrap up the Zebulon's Guide to the Rim for magazine publication.<br /><br />At anyrate, if you look at the above link Will suggested a rank structure that while it has various names and such taken from the bird/wing motiff of the Flight it really looks like a human style rank structure. I got asking myself whether an alien culture would develop something so recognizable to a human. The UPF rank structure looks like something a human would use and why not? Human are a major player in the UPF. However the Rim will have already developed its naval traditions long before the UPF is discovered.<br /><br />So... is there a reason why a rank structure MUST follow the traditional enlisted and officer structure?<br /><br />What would an alien rank structure look like?<br /><br />I'd like the military members to sound off on this, please.<br /><br />