It's a pity that unvarnished truth is always scarce but in any event the vacancies from WO down to L/S must be given an accumulated figure and added to any vacancies in the overall A/B rates. You cannot be down over 70 NCO's and claim NO vacancies in junior seaman of various Branches. If you declare that you are short 46 L/S then you can ONLY find them in your NON NCO strengths subject to training. It is the same maths for commissioned ranks which relies in strengths within Cadet, Ensign, and Sub-Lieutenants, to eventually fill vacancies on promotion. In other words Recruit and Train.