Bureaucratic / written register.
拨 here means 'to allot from a larger pool' (as in
拨款 bō-kuǎn 'allocate funds');
拨用 specifically pairs that allotment with
用 'to be used for', so it implies 'allocated AND being put to use'. Compare
调用 (diào-yòng, to redirect for use) which has no allocation step.
