In the Navy, "XO" is short for this person
(A Guide to Navy Abbreviations and ... [PAR] U.S. MILITARY ABBREVIATION AND ACRONYM LIST ..... Detailer: the person 
assigned with the task of placing a qualified future Sailor, recruit or Sailor ...... XO: 
Executive Officer; Naval Officer who is second-in-command, reporting to the CO. [DOC] [TLE] Naval Terminology, Jargon and Slang FAQ - Haze Gray & Underway [PAR] Oct 31, 2003 ... Nub  Newbie, or someone who does not stand watches and is therefore ...