As a flag
This determines whether the building will automatically promote any infantry that enter it to Elite status. The Template:TTL flag on the building can be used to restrict the number of infantry that can be promoted by this armory. Once it has promoted this number of infantry it is no longer functional. Multiple units can be selected at once and ordered into the armory, this causes them to form a "queue", similar to when multiple units are ordered into a transport, and wait for the people ahead of them to finish in the armory before entering.
When an infantry unit enters an Armory it dissapears and, after a short time has passed, reappears accompanied by the unit promoted effects (the unit briefly flashes and a sound effect is played), although not the EVA announcement. However, the unit appears in the upper left corner of the building and does not 'exit' (i.e. move away from the building), even if a rally point is set. In order to promote the next unit, the first unit must first be selected and ordered to move away from the building. If units are "queued" (see above) then the next unit will enter the armory automatically as soon as the unit ahead of it leaves.