Catchment
From OpenTTD
The Catchment Area of a station is the radius around the stage that it can service. Town-buildings and industries that are within a station's catchment area accept cargo through this station, and will place their cargo at the station to be delivered elsewhere.
Every industry square can provide the cargo producet by that industry.
In some industries only certain squares can accept the cargo required by that industry. (You can use the land area information tool to find out which square accept cargo. And when building a station you can turn on information about which types of cargo will be acceped by industries in the catchment area).
[edit] Catchment Area and Station Rating
When a building is covered by multiple catchment areas, the station with the highest rating will get the largest part of the cargo.
Notice that when three or more catchment areas cover the same building, only the two catchment areas with the highest ratings will get cargo.
