The map_matrix contains the data that associates the graphically generated maps to the map values.
Pokemon DPPt- root/fielddata/mapmatrix/map_matrix.narc
Pokemon HGSS- root/a/0/4/1
|0x00||Uint8||Width of Global Map|
|0x01||Uint8||Height of Global Map|
|0x04||Uint8||Number of Characters of Map Prefix|
|0x05||Char*||Map Prefix Name|
* Length determined by 0x04
** Length of data is Height X Width
Data In Use
Let Height = 3, Width = 3, Data = ABCDEFGHI, Map Prefix = ExMap (so prefix length is 5)
[[A B C] [D E F] [G H I]]
This illustrates that the value at B goes with the map named ExMap00_01c because B is (0,1) in the above matrix. The map names are declared within the proper land_data[_release] files.
The value of B is the map value, that is, the value of the index of the map (where 411 is Twinleaf Town in DPPt and 60 is New Bark Town in HGSS).