acting
An acting rank is a designation that allows a soldier to assume a military rank—usually higher and usually temporary. They may assume that rank either with or without the pay and allowances appropriate to that grade, depending on the nature of the acting promotion. An acting officer may be ordered back to the previous grade. This situation may arise when a lower-ranking officer is called upon to replace a senior officer, or fill a position higher than the current rank held.
lower-ranking officer is called upon to replace a senior officer, or fill a position higher than the current rank held
military terminology