Lucas pulled the rank 'Commander' out of the bag to give to Luke to show his new rank within the rebel alliance. Since then EU writers have tried to fit it into a rank structure. In the Rebel Alliance/New Republic military (which is based on the Old Republic model) the Rank of Commander is used by all three main branches (Army, Navy, Starfighter command). It fits inbetween Colonel and General in the Army and Starfigher corps and between Captain and Admiral Ranks in the Navy. This is illustrated in serveral books where Commander Wedge Antilles is considered Junior to Admiral Akbar and General Salm but senior to Colonel Celchu and (Navy) Captain Onoma. It seems to be given to personel that are in command of a joint ad-hoc force of several units such as a Capital Ships Fighter Wing or in command of a senior elite unit (Such as Luke and then Wedge in command of Rogue Squadron). It is roughly equal to a rank such as Commodore or Brigadier General in Earth military forces. This leads to confusion as most struggle with the concept of a 'Commander' outranking a 'Captain' in the Navy but this is very much the case in the Star Wars universe. It's much the same as a ship class called 'Star Destroyer' but fulling the role of line of battle ship, just need to understand that it's a long time ago and a galaxy far far away so things don't match up exactly to our military ranks here on Earth TL-DR = Yes! We should be able to get 'Commander' as our 'final' rank.