15. A geographic database construction for representing navigable road segments located in a geographic region and that facilitates a presentation of a preview of a calculated route, the geographic database construction comprising: plural sets of data comprising: routing data that include a first set of data entities representing the navigable road segments and containing data used for route calculation; and name data that include a second set of data entities containing names of the navigable road segments, wherein each of the data entities of the first set that represents a navigable road segment that is known by a name includes a reference to a data entity in the second set that contains the name.
15. A geographic database construction for representing navigable road segments located in a geographic region and that facilitates a presentation of a preview of a calculated route, the geographic database construction comprising: plural sets of data comprising: routing data that include a first set of data entities representing the navigable road segments and containing data used for route calculation; and name data that include a second set of data entities containing names of the navigable road segments, wherein each of the data entities of the first set that represents a navigable road segment that is known by a name includes a reference to a data entity in the second set that contains the name. 16. The invention of claim 15 wherein each of the data entities of the first set that represents a navigable road segment that is known by plural names includes references to those data entities in the second set that contain the names.