IAP File Format

Applies to:
BG1, BG1: TotS, BG2, BG2: ToB, PST, IWD, IWD:HoW, IWD:TotL, IWD2

General Description
This file format allows for the automatic installation of files. Files can be copied to any path, and TBG files will be automatically unpacked and added to the game (including any associaed strings).

Detailed Description
Overall Structure:

Offset Size (datatype) Description
0x0000 4 (Char Array) Signature ("IAP ")
0x0004 4 (dword) Null
0x0008 4 (dword) Count of TBG files
0x000c 4 (dword) Count of other files
0x0010 1 (Byte) Infinity Engine ID
  • value 0x01- Baldur's Gate
  • value 0x02- Planescape: Torment
  • value 0x03- Icewind Dale
  • value 0x04- Baldur's Gate II: Shadows of Amn
0x0011 4 (dword) Total IAP File Length

The file header is used for both TBG files and any other files present in the IAP. TBG files are always listed first.

Offset Size (datatype) Description
0x0000 4 (dword) Offset (from start of file) to filename
0x0004 4 (dword) Length of filename
0x0008 4 (dword) Launch file on IAP Completion (TXT or RTF)
  • value 0x00- No
  • value 0x01- Yes
0x000C 4 (dword) Offset (from start of file) to file
0x0010 4 (dword) Length of file

This is the actual text for the file names of the individual files.

This is the actual file data.