A mobile data terminal (MDT) is a computerized device used in public transit vehicles, taxicabs, courier vehicles, service trucks, commercial trucking fleets, military logistics, fishing fleets, warehouse inventory control, and emergency vehicles to communicate with a central dispatch office. They are also used to display mapping and information relevant to the tasks and actions performed by the vehicle such as CAD drawings, diagrams & safety information. Mobile data terminals feature a screen on which to view information and a keyboard or keypad for entering information, and may be connected to various peripheral devices. Standard peripherals include two-way radios and taximeters, both of which predate computer assisted dispatching. MDTs may be simple display and keypad units, intended to be connected to a separate black-box or AVL (see below) computer. While MDTs were originally dumb terminals most have been replaced with fully functional PC hardware, known as MDCs (Mobile Digital Computers). While the MDC term is more correct, MDT is still widely used. Other common terms include MVC (Motor Vehicle Computer) and names of manufacturers such as iMobile or KDT