1. A method for storing and accessing data in databases of a computerized travel reservation system, comprising the steps of: providing in the computerized travel reservation system a database system storing database data comprising data used for the sale of reservation products and including service information data applicable to flights, the database system comprising a database to store rules created for accessing the database data in the database system; defining a list of market pairs each comprised of an origin market and a destination market, each rule comprising a criteria section comprising at least one criterion defining flights to which the rule is applicable, and each rule further comprising a content section comprising data corresponding to a type of service information data applicable to said applicable flights, the at least one criterion in each rule being a market pair, the market pair comprising: i) an origin market defining a geographic zone of departure of a flight, and ii) a destination market defining a geographic zone of arrival of the flight, the origin market and the destination market each correspond to at least one geographic zone type selected from a set of zone types comprised of a plurality of coherently defined geographic zone types each having a geographic precision that differs from a geographic precision of others of the plurality of geographic zone types; storing in the database system a table containing the plurality of coherently defined geographic zone types and a priority rank having a value that is associated with each individual one of the plurality of geographic zone types, the values being in a range of values from a smallest value associated with a most-precise geographic zone type to a largest value associated with a least precise geographic zone type; receiving a request for a flight search at the computerized travel reservation system, where the request for the flight search comprises an origin market and a destination market, accessing in the database system the database to find rules with market pairs agreeing with both the origin market and the destination market received with the request for the flight search, for those rules found to have market pairs agreeing with both the origin market and the destination market, for each found rule, the computerized travel reservation system accessing the table of the geographic zone types and computing the priority value of each market pair that agrees with both the origin market and the destination market, and returning one of the stored rules based on a priority of a selected market pair as indicated by the value of the priority rank associated with the geographic zone type of the origin market and the value of the priority rank associated the geographic zone type of the destination market of the selected market pair, where returning returns, as a response to the request for the flight search that comprises at least the origin market and the destination market, the content of the rule having the market pair with a best computed priority value, the returned content comprising the data for the applicable service information for flights that correspond to at least the specified origin market and destination market.