Dispatch is a procedure for assigning employees (workers) or vehicles to customers. Industries that dispatch include taxicabs, couriers, emergency services, as well as home and commercial services such as maid services, plumbing, HVAC, pest control and electricians. With vehicle dispatching, clients are matched to vehicles according to the order in which clients called and the proximity of vehicles to each client's pick-up location. Telephone operators take calls from clients, then either enter the client's information into a computer or write it down and give it to a dispatcher. In some cases, calls may be assigned a priority by the call-taker. Priority calls may jump the queue of pending calls. In the first scenario, a central computer then communicates with the mobile data terminal located in each vehicle (see computer assisted dispatch); in the second, the dispatcher communicates with the driver of each vehicle via two-way radio. With home or commercial service dispatching, customers usually schedule services in advance and the dispatching occurs the morning of the scheduled service. Depending on the type of service, workers are dispatched individually or in teams of two or more. Dispatchers have to coordinate worker availability, skill, travel time and availability of parts. The skills required of a dispatcher are greatly enhanced with the use of computer dispatching software (see computer aided call handling). Manual dispatch systems The following are examples of manual systems used to track the status of resources in a dispatched fleet. Cards Card systems employ a set of shelves with a slot for each unit in the dispatch fleet. Each vehicle or resource has a slot in the shelving system. In it, a card, like a time card used to track an employee's work hours, is stored. A time clock, similar to the one that stamps work hours on a time card, is used to stamp event times on each card. At the beginning of a work day, the resource's identifier or other information is handwritten on the card. Each time the resource's status changes, the card is punched in the time clock and a new status entry is handwritten on the card. The card collects a series of entries through the work shift. In a tow truck example, the card might be labeled with the tow car's radio identifier, "Downtown 6" and may be labeled with the vehicle number or data about the capabilities of the specific tow car. It