idgrid.tbl

This file contains 40 regions of maximum 256 provinces. The first region lies on the top left corner of the map, and the rest follows in a bottom-right fashion: the next one is under the previous one. Once you "fall" off the bottom of the map, the next region restarts at the top, but right of the last "column" of regions.

Region flow

As you can see, this means that the bottom and rightmost regions are smaller than the other ones.

File Info

Location » (eu2 root)\map\idgrid.tbl
Size » 40.960 bytes (40 KB)

File format

The layout of this file is pretty simple. It effectively contains 40 blocks of 256 items of 4-byte integers. Thus, each block is exactly one KB is size.

The items themselves are province-id's. Not all items in a block are used: once you read a zero (except if it is the first item of a block) you know there won't be any more relevant values in that block (another way to look at it is when you read 2 consecutive zero values you know the list is done).
The first item is always 0, it denotes the Terra Incognita province (which happens to be province 0). In other words, each region references the TI province.

The indexes in the list are important: the blocks in ingrid.tbl reference to these values.

Usability

Since this information is tied to incgrid.tbl, check the format description of that file for more info.