map. Saint Proximal Medical Center ambulance is identified by the notation P while Distal Volunteer Rescue Squad is noted with a D. Each zone of the grid is identified with a progression of ambulance zones and fire stations. One zone might be labeled: DP241. This means fire station 2, then 4, then 1, then 3 would respond to a fire call occurring inside this zone. If fire stations 2, 4, and 1 were assigned to calls, Station 3 would be sent to this zone. Distal Volunteer Rescue Squad would be first-up for an ambulance call occurring inside zone DP241. The predefined order is created by persons with expertise in the service being provided, local geography, traffic, and patterns in calls for service. In assigning resources to a zone, decision-makers may consider that responding units must drive around freeways, lakes, or terrain obstructions in order to reach a zone. Zone boundaries and designations will periodically change as communities grow or lessons are learned during day-to-day operations. Consider a zone with an irrigation canal defining one boundary. If a car crashes into the canal, which zone is it in? Zone systems may include standby, move-up, or backfill points. For example, taxi drivers working in a certain zone in the evening hours may expect night club patrons to need a ride. Consider a standby point at Main Street and Railroad Avenue named N. Some fares will come from radio calls to dispatch. A taxi driver, Car 4, may go to predefined standby location N. In some dispatching systems, the driver will call the dispatcher and report they are available and located at standby point N. The dispatcher may respond by reporting the driver's position in the queue, "Car 4, second N." The first call in this district would go to the driver ahead of Car 4. Car 4 would be assigned the second call. If automatic vehicle location is available, it would display service vehicle locations on a map. The closest unit would be interpreted by the dispatcher looking at vehicle locations projected on the map. See also Flight dispatcher Key telephone system Private branch exchange Public-safety answering point Taxi dispatching References External links Emergency Medical Dispatch Trainee Guide, Volume 1 or Job Description of a Truck Dispatcher Logistics