These supply points are also used to provide military engineering services, such as the recovery of defective and derelict vehicles and weapons, maintenance of weapons in the field, the repair and field modification of weapons and equipment; and in peacetime, the life-extension programmes undertaken to allow continued use of equipment. One of the most important role of logistics is the supply of munitions as a primary type of consumable, their storage, and disposal.
The IRT model underlying ASVAB scoring is the three-parameter logistic (3PL) model. The 3PL model represents the probability that an examinee at a given level of ability will respond correctly to an individual item with given characteristics. Specifically, the item characteristics represented in the 3PL model are difficulty, discrimination (i.e., how well the item discriminates among examinees of differing levels of ability), and guessing (i.e., the likelihood that a very low ability examinee would respond correctly simply by guessing).