Is Nomura's word not good enough? Before this I've mentioned that when their names are spelt in Roman alphabets, there will surely be an "X", right? The truth is that when the "X" is taken away, the alphabets that are left behind is an anagram of the members' real names when they were humans. I actually wanted to insert an event scene showing how Roxas got his name. First the word "SORA" popped up and those letters were rearranged into "ROAS" and BAM, suddenly the "X" got inserted in the middle and he was told "Take this name...." Well, I had an image like that but it was something difficult to do time-wise so I gave up.  (Feeling chatty? ) (Edits!)