This file contains information on the activity of aliens in both countries and regions. The same format is used for XCOM.DAT only it obviously applies to XCOM activity in the area.
The format is rather tedious and the best line width is 124 bytes, which will cover an entire month of both Countries and Regions. There are a total of 12 months stored in this file. Each value is stored in 4 bytes in the usual low then high manner. It is signed and will go negative after FF FF FF 7F (0x7FFFFFFF in normal notation), for ALIEN.DAT negative values will not occur, but they are possible in the XCOM.DAT when missions go bad. Very high or highly negative values in these files (certainly once you get up to 2 billion or so) will cause the game to freeze up if you try to view the graphs.
The first record contains this month's information. The second last month's and so on. Each UFO adds one to the appropriate territory it is over on each 30 minute update period, so a score of 100 would indicate UFOs spent 50 hours (roughly) over that territory in the month. If it is over a specific country, it will also add one to that counter each 30 minutes, as well as incrementing the territory. There are also other, more rapid, ways of the Aliens scoring that will be recorded here.
For XCOM the same basic method happens, but different things will score points - for example shooting down a very small ufo (100 points) in the UK would add 100 to UK, and 100 to Europe, downing the same craft would get 50, and completing a 25 point mission would gain 25 in both the UK and Europe. Negative values would also be added, decreasing the score and potentially making it negative (shows as 0 on graph, but is actually stored as a negative number internally).
These offsets were completely ripped from Hatfarm's website, with some rearrangement to aid look-up (hopefully)
|0 (0x0)||USA||64 (0x40)||North America|
|4 (0x4)||Russia||68 (0x44)||Arctic|
|8 (0x8)||UK||72 (0x48)||Antarctica|
|12 (0xC)||France||76 (0x4C)||South America|
|16 (0x10)||Germany||80 (0x50)||Europe|
|20 (0x14)||Italy||84 (0x54)||North Africa|
|24 (0x18)||Spain||88 (0x58)||Southern Africa|
|28 (0x1C)||China||92 (0x5C)||Central Asia|
|32 (0x20)||Japan||96 (0x60)||Southeast Asia|
|36 (0x24)||India||100 (0x64)||Siberia|
|40 (0x28)||Brazil||104 (0x68)||Australasia|
|44 (0x2C)||Australia||108 (0x6C)||Pacific|
|48 (0x30)||Nigeria||112 (0x70)||North Atlantic|
|52 (0x34)||South Africa||116 (0x74)||South Atlantic|
|56 (0x38)||Egypt||120 (0x78)||Indian Ocean|