Patent ID: 8543618

Claim:
A map data update apparatus having a link list for link management in map data by using update data that updates the link list, the update data specifies position information of a subject link to be updated in the link list, the apparatus comprising: a memory configured to store a link list; and a processor, the processor configured with a link addition enhancer for enhancing the link list stored in the memory so that the link list includes the position information specified by the update data, when the position information is currently non-existent in the link list; an information update unit for updating information on the link in the memory that is in association with the position information specified by the update data based on the update data, wherein each of the links represents a road in the map data, successive links respectively having same road attributes are defined as a link series in the map data, each of the links in a specific link series has reference information to point to an immediate subsequent link of said each of the links in the specific link series, a last link in the link series has a nonexistent pseudo-link that serves as the immediate subsequent link of the last link in the link series, the processor is further configured to divide an existing link into two links, the existing link of the link series, before the existing link is divided into the two links, has reference information to point a link N as the immediate subsequent link of the existing link, the existing link, after being divided into the two links, remains the existing link as indicated by having a same link identifier, and the link series then further includes a new link divided from the existing link, the new link has reference information to point to the link N as the immediate subsequent link of the new link in the link series, and the existing link after being divided has reference information changed to point the new link as the immediate subsequent link of the existing link in the link series.