ITM file format

BG1, BG1: TotS, BG2, BG2: ToB, IWD, IWD:HoW, IWD:TotL

This file format describes an "item". Items include weapons, armor, books, scrolls, rings and more. Items can have attached abilties, occuring either when a target creature it hit, or when the item is equipped. ITM files have a similar structure to SPL files.

ITM files consist of a main header, zero or more extended headers (each containing zero or more feature blocks) and zero or more casting feature blocks. All the feature blocks are stored as a continuous data segment, with each extended header containing an offset into this data, and the main header containing an offset into this data for the casting feature blocks.
NB. A creature must meet the minimum stat requirements to be able to converse with an item.

Overall structure:

Header

Extended Headers

Equipping Feature Blocks

Offset	Size (datatype)	Description
0x0000	4 (char array)	Signature ('ITM ')
0x0004	4 (char array)	Version ('V1 ')
0x0008	4 (strref)	Unidentified Name (strref)
0x000c	4 (strref)	Identified Name (strref)
0x0010	8 (resref)	Replacement Item (resref)
0x0018	4 (dword)	Flags
0x001c	2 (word)	Item type
0x001e	1*4 (byte)	Usability bitmask
0x0022	2 (char array)	Item animation
0x0024	2 (word)	Min Level
0x0026	2 (word)	Min Strength (unused in BG1)
0x0028	1 (byte)	Min Strength Bonus (unused in BG1) Note: A strength of 19 or above is considered to have a Strength Bonus of 0, and would therefore not be able to equip any weapon with a Strength Bonus restriction.
0x0029	1 (byte)	Kit Usability 1
0x002a	1 (byte)	Min Intelligence (unused in BG1)
0x002b	1 (byte)	Kit Usability 2
0x002c	1 (byte)	Min Dexterity (unused in BG1)
0x002d	1 (byte)	Kit Usability 3
0x002e	1 (byte)	Min Wisdom (unused in BG1)
0x002f	1 (byte)	Kit Usability 4
0x0030	1 (byte)	Min Constitution (unused in BG1)
0x0031	1 (byte)	Weapon Proficiency
0x0032	2 (word)	Min Charisma
0x0034	4 (dword)	Price
0x0038	2 (word)	Stack amount
0x003a	8 (resref)	Inventory icon
0x0042	2 (word)	Lore to ID
0x0044	8 (resref)	Ground icon
0x004c	4 (dword)	Weight
0x0050	4 (dword)	Unidentified Description (strref)
0x0054	4 (dword)	Identified Description (strref)
0x0058	8 (resref)	Description icon
0x0060	4 (dword)	Enchantment
0x0064	4 (dword)	Offset to extended headers
0x0068	2 (word)	Count of extended headers
0x006a	4 (dword)	Offset to feature blocks
0x006e	2 (word)	Index into equipping feature blocks
0x0070	2 (word)	Count of Equipping Feature Blocks

Items can have several "abilities" that correspond to an action the item can do (e.g. melee attacks, projectile attacks, spell-casting etc.). Each of these abilities is specified through an extended header. Only the first three extended headers can have charges (extended headers further than this use the charges of the first extended header). Tooltips for item abilities are set through tooltips.2da.

NB. For items to be stackable, they must contain at least one extension header, even if it is empty.
NB. For an attack type of projectile, if the projectile type is set to 1,2 or 3, the weapon will use the attack speed of the ammunition.

Offset	Size (datatype)	Description
0x0000	1 (char)	Attack type 0 = None 1 = Melee 2 = Projectile 3 = Magic 4 = Launcher
0x0001	1 (char)	ID Req. bit 0: ID Required bit 1: Non-ID Required
0x0002	1 (char)	Location 0 = None 1 = Weapon 2 = Spell 3 = Equipment 4 = Innate
0x0003	1 (char)	Alternative dice sides
0x0004	8 (resref)	Use icon
0x000c	1 (char)	Target type 0 = Invalid (cannot be selected) 1 = Creature 2 = Crash 3 = Character potrait 4 = Area 5 = Self 6 = Crash 7 = None (Self, ignores game pause)
0x000d	1 (char)	Target count
0x000e	2 (word)	Range
0x0010	1 (byte)	Projectile type 0 = None 1 = Arrow 2 = Bolt 3 = Bullet 40 = Spear 100 = Throwing Axe
0x0011	1 (byte)	Alternative dice thrown
0x0012	1 (byte)	Speed
0x0013	1 (byte)	Alternative damage bonus
0x0014	2 (word)	THAC0 bonus A successful hit will always occur if any of the conditions below is true This field is set to 32767 The target creature(s) is STATE_HELPLESS The target is affected by time stop
0x0016	1 (byte)	Dice sides
0x0017	1 (byte)	Primary type
0x0018	1 (byte)	Dice thrown
0x0019	1 (byte)	Secondary type
0x001a	2 (word)	Damage bonus
0x001c	2 (word)	Damage type 0 = None 1 = Piercing/Magic 2 = Blunt 3 = Slashing 4 = Ranged 5 = Fists 6 = Piercing/Blunt (more) (BG2) 7 = Piercing/Slashing (more) (BG2) 8 = Blunt/Slashing (less) (BG2)
0x001e	2 (word)	Count of feature blocks
0x0020	2 (word)	Offset to feature blocks
0x0022	2 (word)	Charges
0x0024	2 (word)	Charge depletion behaviour 0 = Don't vanish 1 = Expended 2 = Expended (w/o sound) 3 = Recharge each day
0x0026	4 (dword)	Flags
0x002a	2 (word)	Projectile animation (projectl.ids/missile.ids)
0x002c	2*3 (word)	Melee animation
0x0032	2 (word)	Bow/Arrow qualifier (0=No, 1=Yes)
0x0034	2 (word)	Crossbow/Bolt qualifier (0=No, 1=Yes)
0x0036	2 (word)	Misc. Projectile qualifier (0=No, 1=Yes)

Any action carried out by an item is done by feature blocks, each of which holds an effect number as well as targetting and timing information. The engine appears to roll a probability for each valid target type, rather than one probability per attack.

Offset	Size (datatype)	Description
0x0000	2 (word)	Opcode number
0x0002	1 (char)	Target type 0=None 1=Self (pre-projectile) 2=Pre-target 3=Party 4=Everyone (inc. party) 5=Everyone (excl. party) 6=Everyone matching specific value of caster (or Party if cast by party member) 7=Everyone matching specific value of target (ranged ability type only, otherwise no target) 8=Everyone (excl. caster) 9=Self (post-projectile)
0x0003	1 (char)	Power
0x0004	4 (dword)	Parameter 1
0x0008	4 (dword)	Parameter 2
0x000c	1 (char)	Timing mode 0=Duration 1=Permanent 2=While equipped 3=Delayed Duration 4=Delayed 5=Delayed (transforms to 8) 6=Duration? 7=Permanent? 8=Permanent (unsaved) 9=Permanent (after Death) 10=Trigger 4096=Absolute duration
0x000d	1 (char)	Resistance The default behaviour is that effects cannot be dispelled and ignore resistance. bit 0: Can be dispelled, affected by resistance bit 1: Ignores resistance (when used in combination with bit 0) This can also be presented in the more traditional way: 0=Nonmagical 1=Can be dispelled/Affected by resistance 2=Cannot be dispelled/Ignores resistance 3=Can be dispelled/Ignores resistance
0x000e	4 (dword)	Duration
0x0012	1 (char)	Probability 1
0x0013	1 (char)	Probability 2 Note: The BG1 engine treats probability as a single word, effects are applied in the range 0-probability. Note: Other engines treat probability as two values, effects are applied in the range probability <= x <= probability. Probability range is 0-99
0x0014	8 (resref)	Resource
0x001c	4 (dword)	Dice Thrown
0x0020	4 (dword)	Dice Sides
0x0024	4 (dword)	Saving throw type bit 0: Spells bit 1: Breathe bit 2: Death bit 3: Wands bit 4: Polymorph NB. If more than 1 saving throw type is specified, the target rolls against their best save.
0x0028	4 (dword)	Saving throw bonus
0x002c	4 (dword)	Special

Bit	Byte 1	Byte 2	Byte 3	Byte 4
0	Unsellable (critical item)*	Silver	Unused	Unused
1	Two-handed	Cold-Iron	Unused	Unused
2	Movable	Unsellable (stolen) / two handed animation Set offhand animations for 0x5###-0x6### animId series (excluding 0x64##) when weapon placed in offhand.	Unused	Unused
3	Displayable	Conversable	Unused	Unused
4	Cursed	Unused	Unused	Unused
5	Cannot scribe to spellbook (scrolls)	Unused	Unused	Unused
6	Magical	Unused	Unused	Unused
7	Bow	Unused	Unused	Unused

* In BG1, this flag does not affect whether the item can be sold.

The item type of an item affects the pick-up/put-down sound when moving the item in the inventory, whether stores will buy the item and the ability ubttons shown on the item description screen.

Code	Item type
0x0000	Books/misc
0x0001	Amulets and necklaces
0x0002	Armor
0x0003	Belts and girdles
0x0004	Boots
0x0005	Arrows
0x0006	Bracers and gauntlets
0x0007	Helms, hats, and other head-wear
0x0008	Keys (not in Icewind Dale?)
0x0009	Potions
0x000a	Rings
0x000b	Scrolls
0x000c	Shields (not in IWD)
0x000d	Food
0x000e	Bullets (for a sling)
0x000f	Bows
0x0010	Daggers
0x0011	Maces (in BG, this includes clubs)
0x0012	Slings
0x0013	Small swords
0x0014	Large swords
0x0015	Hammers
0x0016	Morning stars
0x0017	Flails
0x0018	Darts
0x0019	Axes (specifically, 1-handed axes -- halberds and 2-handed polearms not included)
0x001a	Quarterstaff
0x001b	Crossbow
0x001c	Hand-to-hand weapons (fist, fist irons, punch daggers, etc)
0x001d	Spears
0x001e	Halberds (2-handed polearms)
0x001f	Crossbow bolts
0x0020	Cloaks and robes
0x0021	Gold pieces (not an inventory item, but can appear as "monster dropped" treasure)
0x0022	Gems
0x0023	Wands
0x0024	Container/eye/broken armor
0x0025	Books/Broken shield/bracelet
0x0026	Familiars/Broken sword/earring
0x0027	Tattoos (PST)
0x0028	Lenses(PST)
0x0029	Buckler/teeth
0x002a	Candle
0x002b	Unknown
0x002c	Clubs(IWD)
0x002d	Unknown
0x002e	Unknown
0x002f	Large Shield(IWD)
0x0030	Unknown
0x0031	Medium Shield(IWD)
0x0032	Notes
0x0033	Unknown
0x0034	Unknown
0x0035	Small Shield(IWD)
0x0036	Unknown
0x0037	Telescope(IWD)
0x0038	Drink(IWD)
0x0039	Great Sword(IWD)
0x003a	Container
0x003b	Fur/pelt
0x003c	Leather Armor
0x003d	Studded Leather Armor
0x003e	Chain Mail
0x003f	Splint Mail
0x0040	Half Plate
0x0041	Full Plate
0x0042	Hide Armor
0x0043	Robe
0x0044	Unknown
0x0045	Bastard Sword
0x0046	Scarf
0x0047	Food(IWD2)
0x0048	Hat
0x0049	Gauntlet

Bit	Byte 1	Byte 2	Byte 3	Byte 4
0	Chaotic...	Cleric/Mage	Fighter/Mage/Thief	Dwarf
1	...Evil	Cleric/Thief	Fighter/Thief	Half-Elf
2	...Good	Cleric/Ranger	Mage	Halfling
3	...Neutral	Fighter	Mage/Thief	Human
4	Lawful...	Fighter/Druid	Paladin	Gnome
5	Neutral...	Fighter/Mage	Ranger	Monk
6	Bard	Fighter/Cleric	Thief	Druid
7	Cleric	Fighter/Mage/Cleric	Elf	Half-Orc

Value(ASCII)	Value(Hex)	Description
" "	2020h	<none>
"2A"	3241h	Leather Armor
"3A"	3341h	Chainmail
"4A"	3441h	Plate Mail
"2W"	3257h	Robe
"3W"	3357h	Robe
"4W"	3457h	Robe
"AX"	4158h	Axe
"BW"	4257h	Bow
"CB"	4342h	Crossbow
"CL"	434Ch	Club
"D1"	4431h	Buckler
"D2"	4432h	Shield (Small)
"D3"	4433h	Shield (Medium)
"D4"	4434h	Shield (Large)
"DD"	4444h	Dagger
"FL"	464Ch	Flail
"FS"	4653h	Flame Sword
"H0"	4830h	Small Vertical Horns
"H1"	4831h	Large Horizontal Horns
"H2"	4832h	Feather Wings
"H3"	4833h	Top Plume
"H4"	4834h	Dragon Wings
"H5"	4835h	Feather Sideburns
"H6"	4836h	Large Curved Horns (incorrect paperdoll image)
"HB"	4842h	Halberd
"MC"	4D43h	Mace
"MS"	4D53h	Morning Star
"QS"	5153h	Quarter Staff (Metal)
"S1"	5331h	Sword 1-Handed
"S2"	5332h	Sword 2-Handed
"SL"	534Ch	Sling
"SP"	5350h	Spear
"SS"	5353h	Short Sword
"WH"	5748h	War Hammer
"S3"	5333h	Katana #
"SC"	5343h	Scimitar #

Bit	Byte 1	Byte 2	Byte 3	Byte 4
0	Cleric of Talos	Stalker Ranger	Diviner	Beserker Fighter
1	Cleric of Helm	Beastmaster Ranger	Enchanter	Wizardslayer Fighter
2	Cleric of Lathlander	Assassin Thief	Illusionist	Kensai Fighter
3	Totemic Druid	Bounty Hunter Thief	Invoker	Cavalier Paladin
4	Shapeshifter Druid	Swashbuckler Thief	Necromancer	Inquisiter Paladin
5	Avenger Druid	Blade Bard	Transmuter	Undead Hunter Paladin
6	Barbarian	Jester Bard	All (no kit)	Abjurer
7	Wildmage	Skald Bard	Ferlain	Conjurer

Value (hex)	Description
00h	None
59h	Bastard Sword
5Ah	Long Sword
5Bh	Short Sword
5Ch	Axe
5Dh	Two-Handed Sword
5Eh	Katana
5Fh	Scimitar/Wakizashi/Ninja-To
60h	Dagger
61h	War Hammer
62h	Spear
63h	Halberd
64h	Flail/Morningstar
65h	Mace
66h	Quarterstaff
67h	Crossbow
68h	Long Bow
69h	Short Bow
6Ah	Darts
6Bh	Sling
6Ch	Blackjack
6Dh	Gun
6Eh	Martial Arts
6Fh	Two-Handed Weapon Skill
70h	Sword and Shield Skill
71h	Single Weapon Skill
72h	Two Weapon skill
73h	Club
74h	Extra Proficiency 2
75h	Extra Proficiency 3
76h	Extra Proficiency 4
77h	Extra Proficiency 5
78h	Extra Proficiency 6
79h	Extra Proficiency 7
7Ah	Extra Proficiency 8
7Bh	Extra Proficiency 9
7Ch	Extra Proficiency 10
7Dh	Extra Proficiency 11
7Eh	Extra Proficiency 12
7Fh	Extra Proficiency 13
80h	Extra Proficiency 14
81h	Extra Proficiency 15
82h	Extra Proficiency 16
83h	Extra Proficiency 17
84h	Extra Proficiency 18
85h	Extra Proficiency 19
86h	Extra Proficiency 20

Value Word 1	Value Word 2	Value Word 3	Data
00h	14h	50h	Dagger
0Ah	19h	41h	Short Sword
32h	32h	00h	Long Sword, Bastard Sword, Scimitar, Battle Axe, Warhammer, Club, Mace, Flail, Morning Star
3Ch	28h	00h	Two-Handed Sword
00h	23h	41h	Halberd
00h	00h	64h	Spear
0Ah	46h	14h	Staff
00h	00h	00h	Any Missile Weapon (Bow, Arrow, CrossBow, Bolt, Sling, Bullet, Throwing Axe, Dart, Throwing Dagger, etc.)
22h	21h	21h	Any Non-Weapon Item (Amulets, Rings, Wands, etc.)

Bit	Byte 1	Byte 2
0	Add strength bonus	Unknown
1	Breakable	Unknown
2	Unknown	Hostile
3	Unknown	Recharges
4	Unknown	Unknown
5	Unknown	Unknown
6	Unknown	Unknown
7	Unknown	Unknown