| 摘要 |
PROBLEM TO BE SOLVED: To suppress decline of access speed to data in a map data storage part 23. SOLUTION: Unit domain discrimination information for discriminating the physical position in the map data storage part 23 is correlated with a discrimination number of data stored on the physical position, and the physical position in the map data storage part 23 storing object data is accessed on reference to a file management table 231 wherein each discrimination number of the data is stored in the ascending order or in the descending order. COPYRIGHT: (C)2007,JPO&INPIT |
