d2s_File_Format.md

Diablo II Save File Format

Orginal text at https://github.com/krisives/d2s-format

Diablo II stores your game character on disk as a .d2s file. This is a binary file format that encodes all of the stats, items, name, and other pieces of data.

Integers are stored in little endian byte order, which is the native byte ordering on a x86 architecture Diablo II is based on.

Header

Each .d2s file starts with a 765 byte header, after which data is of variable length.

Byte 71 - 89	Byte 92 - 96	Byte	Length	Desc
0	0	0	4	Signature (0xaa55aa55)
4	4	4	4	Version ID
	8	8	4	File size
	12	12	4	Checksum
	16	16	4	Active Weapon
8	20	20	16	Character Name for versions 71 - 97, otherwise 0x00
24	36	36	1	Character Status
25	37	37	1	Character Progression
26			1	Active Weapon for versions 71 - 89
27	38	38	1	? always zero
28			1	? 0x3F for versions 87 - 89, otherwise 0xDD for version 71
29			1	? 0x00 for versions 87 - 89, otherwise 0x01 for version 71
30			1	? 0x10 for versions 71 - 89
31			1	? 0x00 for versions 71 - 89
32			1	? 0x82 for versions 71 - 89
33	39	39	1	? always zero
34	40	40	1	Character Class
35	41	41	1	? 0x10 for versions 92+, otherwise 0x00 for versions 71 - 89
	42	42	1	? 0x1E for versions 92+
36	43	43	1	Level
37			1	? 0x00 for versions 71 - 89
	44	44	4	Created unix timestamp?
	48	48	4	Last Played unix timestamp
	52	52	4	? 0xFF all bytes for versions 92+
38			32	Character Menu Appearance for versions 71 - 89
	56	56	64	Assigned Skills for versions 92+
70			16	Assigned Skills for versions 71 - 89
86			1	Left Mouse for versions 71 - 89
	120	120	4	Left Mouse for versions 92+
87			1	Right Mouse for versions 71 - 89
	124	124	4	Right Mouse for versions 92+
	128	128	4	Left Mouse (weapon switch) for versions 92+
	132	132	4	Right Mouse (weapon switch) for versions 92+
	136	136	32	Character Menu Appearance for versions 92+
88			1	first 4 bits difficulty, last 4 bits starting act for versions 71 - 89
89			37	? 0x00 for versions 71 - 89
	168	168	3	Difficulty
126	171	171	4	Map ID
	175	175	2	? 0x00 for versions 92+
	177	177	2	Merc dead? for versions 92+
	179	179	4	Merc seed? for versions 92+
	183	183	2	Merc Name ID for versions 92+
	185	185	2	Merc Type for versions 92+
	187	187	4	Merc Experience for versions 92+
	191		140	? 0x00 for versions 92 - 96
		191	28	? 0x00 for versions 97+
		219	48	D2R Character Menu Appearance for versions 97+
		267	16	Character Name for versions 98+, otherwise 0x00 for version 97
		283	48	? 0x00 for versions 97+
	331	331	1	? 0x00 for versions 97+, otherwise 0x01 for versions 92 - 96
	332	332	3	? 0x00 for versions 92+
130	335	335	298	Quest
428	633	633	80	Waypoint
508	713	713	52	NPC
560	765	765		Attributes
			32	Skills
				Items

Versions

File version. The following values are known:

• 71 is 1.00 through v1.06
• 87 is 1.07 or Expansion Set v1.08
• 89 is standard game v1.08
• 92 is v1.09 (both the standard game and the Expansion Set.)
• 96 is v1.10 - v1.14d
• 97 is D2R v1.0.x - v1.1.x
• 98 is D2R v1.2.x - v1.3.x (Patch 2.4)
• 99 is D2R v1.4.x+ (Patch 2.5)

Checksum

To calculate the checksum set the value of it in the .d2s data to be zero and iterate through all the bytes in the data calculating a 32-bit checksum:

code in C

    sum = (sum << 1) + data[i];

code in JavaScript

source: krisives/d2s-format#5

const fs = require("fs");
const path = require("path");
const file = path.join(process.cwd(), "path_to_save.d2s");

function calculateSum(data) {
  let sum = 0;
  for (let i = 0; i < data.length; i++) {
    let ch = data[i];
    if (i >= 12 && i < 16) {
      ch = 0;
    }
    ch += sum < 0;
    sum = (sum << 1) + ch;
  }

  return sum;
}

function littleToBigEndian(number) {
  return new DataView(
    Int32Array.of(
      new DataView(Int32Array.of(number).buffer).getUint32(0, true)
    ).buffer
  );
}

function ashex(buffer) {
  return buffer.getUint32(0, false).toString(16);
}

async function readSafeFile() {
  return await new Promise((resolve, reject) => {
    fs.readFile(file, (err, data) => {
      if (err) return reject(err);
      return resolve(data);
    });
  });
}

async function writeCheckSumToSafeFile(data) {
  return await new Promise((resolve, reject) => {
    fs.writeFile(file, data, err => {
      if (err) reject(err);
      resolve();
    });
  });
}

readSafeFile().then(data => {
  const sum = calculateSum(data);
  const bufferSum = littleToBigEndian(sum);
  const hex = ashex(bufferSum);
  const newData = data;
  for (let i = 0; i < 4; i++) {
    newData[12 + i] = bufferSum.getInt8(i);
  }
  writeCheckSumToSafeFile(newData).then(() => console.log(hex));
});

code in golang

source: https://github.com/gucio321/d2d2s/blob/66f91e2af7b3949ca7f279aae397bd8904519e2d/pkg/d2s/d2s.go#L397

// CalculateChecksum calculates a checksum and saves in a byte slice 
func CalculateChecksum(data *[]byte) {
        var sum uint32
        for i := range *data {
                sum = ((sum << 1) % math.MaxUint32) | (sum >> (int32Size*byteLen - 1))

                sum += uint32((*data)[i])
        }

        sumBytes := make([]byte, int32Size)
        binary.LittleEndian.PutUint32(sumBytes, sum)

        const (
                int32Size = 4
                checksumPosition = 12
        )
        for i := 0; i < int32Size; i++ {
                (*data)[checksumPosition+i] = sumBytes[i]
        }
}

If the checksum is invalid, Diablo II will not open the save file.

Active Weapon

This value is either 0 or 1 indicating which weapons/shield/spell setup is in use

Character Name

Character names are store as an array of 16 characters which contain a null terminated string padded with 0x00 for the remaining bytes. For for versions 98+ characters are stored as UTF-8 while for older version it is stored as 7-bit ASCII. To be valid, they must follow these rules:

• Must be 2-15 bytes in length
• Must begin with a letter
• May contain up to one hyphen (-) or, since versions 89, underscore (_)
• For versions 71 - 97, contains 7-bit ASCII letters while for versions 98+, contains utf-8 characters

Character Status

This is a 8-bit field:

Bit	Desc
0	?
1	?
2	Hardcore
3	Died (if hardcore, idicates character can't be played)
4	?
5	Expansion
6	Ladder
7	?

Character Progression

This is a 8-bit field representing the Title your character gets after completing a difficulty. Non-Expansion has upper 2 bits set (00, 01, 10 or 11), while Expansion has both the upper and lower 2 bits set to the same 2 bit value (00, 01, 10 or 11)

Value	Standard (Classic)	Hardcore (Classic)
0x00	No Title	No Title
0x10	Slayer (Sir/Dame)	Destroyer (Count/Countess)
0x01	Champion(Lord/Lady)	Conqueror (Duke/Duchess)
0x11	Patriarch/Matriarch (Baron/Baroness)	Guardian (King/Queen)

Character Class

ID	Class
0	Amazon
1	Sorceress
2	Necromancer
3	Paladin
4	Barbarian
5	Druid (Expansion only)
6	Assassin (Expansion only)

Level

This level value is visible only in character select screen and must be the same as this in Stats section.

Assigned skills

Assigned skills section is a an array of 16 skill ids mapped to a hotkey, each a 4 byte integer (uint32). If no skill is assigned the value is 0x00.

Character Menu Appearance

32 byte structure which defines how the character looks in the menu. Does not change in-game look

D2R Character Menu Appearance

48 byte structure which defines how the character looks in the menu, extends the information given in pre-D2R versions. Does not change in-game look

Difficulty

3 bytes of data that indicates which of the three difficulties the character has unlocked. Each byte is representitive of one of the difficulties. In this order: Normal, Nightmare, and Hell. Each byte is a bitfield structured like this:

7	6	5	4	3	2, 1, 0
Active?	Unknown	Unknown	Unknown	Unknown	Act (0-4)

Quest

The quests struct is a 298 byte section that describes all quests in the game but also contains data about act traveling. Each quest is 2 bytes long, with the following important bits:

Bit	Description
0	Quest completed
1	Requirements Met
2	Quest Given
6	Drank potion of Life (Act III)
8	Read Scroll of Resistance (Act V)
11	Secret Cow Level Complete (Act I)
12	Quest Closed
13	Quest Completed in Current Game

Header

Byte 71 - 89	Byte	Length	Desc
130	335	4	Woo! { 0x57, 0x6F, 0x6F, 0x21 }
134	339	4	Version: { 0x06, 0x00, 0x00, 0x00 }
138	341	2	Size: 298 bytes

Structure

This structure repeats it self 3 times, once for Normal, Nightmare and Hell. The offset is the offset into the quest structure.

Offset 71	Offset	Length	Description
0	0	2	Set to 1 if you have been introduced to Warriv in Act I.
2	2	12	All six quests for Act I.
14	14	2	Set to 1 if you have traveled to Act II.
16	16	2	Set to 1 if you have been introduced to Jerhyn.
18	18	12	All six quests for Act II.
30	30	2	Set to 1 if you have traveled to Act III.
32	32	2	Set to 1 if you have been introduced to Hratli.
34	34	12	All six quests for Act III.
46	46	2	Set to 1 if you have traveled to Act IV.
48	48	2	Set to 1 if you have been introduced to Act IV. (which you have if you have traveled)
50	50	12	Act IV only has 3 quests, so the struct has 6 empty bytes here.
	62	2	Set to 1 if you have traveled to Act V.
62		30	Some kind of padding after all the quest data.
	64	2	Seems to be set to 1 after completing Terror's End and talking to Cain in act IV.
	66	4	Seems to be some kind of padding.
	70	12	All six quests for Act V.
	82	1	Set to 1 if you went to Akara to reset your stats already
	83	1	Seems to be set to 0x80 after completing the Difficulty Level
	84	12	Some kind of padding after all the quest data.
92		12	If this is the Hell structure, padding to reach 298 total bytes, otherwise doesn't exist

Waypoint

Header

Byte 71 - 89	Byte	Length	Desc
428	633	2	WS { 0x57, 0x53 }
430	636	4	Version: { 0x01, 0x00, 0x00, 0x00 }
434	640	2	Size: 80 bytes

Structure

This structure repeats it self 3 times, once for Normal, Nightmare and Hell. The offset is the offset into the waypoint structure.

Offset	Length	Description
0	2	Marker {0x02, 0x01}
2	8	Waypoint bitfield in order of least significant bit
10	14	Some kind of padding

In the waypoint bitfield, a bit value of 1 means that the waypoint is enabled. It is in an order from lowest to highest, so 0 is Rogue encampment (ACT I) etc. The first waypoint in each difficulty is always activated.

NPC

Header

Byte 71 - 89	Byte	Length	Desc
508	713	2	{ 0x01, 0x77 }
510	715	2	Size: 52 bytes

Introductions Structure

This structure repeats it self 3 times, once for Normal, Nightmare and Hell. The offset is the offset into the NPC Introductions structure indicating which NPC has introduced themselves.

Offset	Length	Desc
0	1	Warriv Act II
1	1	?
2	1	Charsi
3	1	Warriv Act I
4	1	Kashya
5	1	Akara
6	1	Gheed
7	1	?
8	1	Greiz
9	1	Jerhyn
10	1	Meshif Act II
11	1	Geglash
12	1	Lysander
13	1	Fara
14	1	Drogan
15	1	?
16	1	Alkor
17	1	Hratli
18	1	Ashera
19	2	?
21	1	Cain Act III
22	1	?
23	1	Elzix
24	1	Malah (Expansion only)
25	1	Anya (Expansion only)
26	1	?
27	1	Natalya
28	1	Meshif Act III
29	2	?
31	1	Ormus
32	5	?
37	1	Cain Act V (Expansion only)
38	1	Qualkehk (Expansion only)
39	1	Nihlathak (Expansion only)
40	24	?

Congratulations Structure

This structure follows the Introduction structures and repeats it self 3 times, once for Normal, Nightmare and Hell. The congratulations structure uses the same offsets as the Introcutions structure but indicates which NPC has congratulated the hero.

It would appear that offsets 1 through 6 get set after you take the caravan to Act II in Normal difficulty. Offsets 1, 14 and 15 get set after you sail to Act III. On entering Act IV, offsets 16, 17, 18, 21, 27, 28 and 31 get set.

When you return to a previous act and talk to the NPC's, these bits are cleared.

Attributes

Following the header is the attributes section, the sections starts with the string identifier of gf and is variable in length.

Offset 71 - 92	Offset	Length	Desc
0	0	2	gf { 0x67, 0x66 }
	2	27-53	An array of 9 bit attribute id, followed by a n bit length attribute value. The section is terminated by a 9 bit value of 0x1ff. It's worth mentioning that these fields are bit reversed. Basically if you find the bits 00100111 they are reversed into 11100100.
2		2	Bit field indicating the the presence or absence of each particular statistic
4		36-64	4 byte array of values for each statistic present according to the bit field, in the order they appear in the bit field

Attribute IDs

ID	Attribute
0	Strength
1	Energy
2	Dexterity
3	Vitality
4	Unused stats
5	Unused skills
6	Current HP
7	Max HP
8	Current mana
9	Max mana
10	Current stamina
11	Max stamina
12	Level
13	Experience
14	Gold
15	Stashed gold

Attribute bit lengths

Bit length	Attribute
10	Strength
10	Energy
10	Dexterity
10	Vitality
10	Unused stats
8	Unused skills
21	Current HP
21	Max HP
21	Current mana
21	Max mana
21	Current stamina
21	Max stamina
7	Level
32	Experience
25	Gold
25	Stashed gold

Example of the reading

for {
    // 1. read 9 bits id. (reverse them)
    // 2. if the id is 0x1ff, terminate the loop
    // 3. read bit length from attribute map for that id.
    // 4. read bit length nr of bits. 
}

Bit Filed For versions 92 or older,

Bit	Attribute
0	Strength, always 1
1	Energy, always 1
2	Dexterity, always 1
3	Vitality, always 1
4	Unused stats
5	Unused skills
6	Current HP
7	Max HP
8	Current mana, always 1
9	Max mana, always 1
10	Current stamina, always 1
11	Max stamina, always 1
12	Level, always 1
13	Experience
14	Gold
15	Stashed gold

Skills

Skills are a 32 byte section containing a 2 byte header with the value if and 30 byte of skill data. Each class has 30 skills available to them, so each skill get 1 byte each. The tricky part about the skill mapping is that each class has a different offset into the Skill map where their class specific skills start, and then go 30 indexes into the map. So for example Assassin has an offset of 251. Which means Assassin skills are between the indexes of 251 and 281 which is exactly 30 indexes.

Layout

Length	Desc
2	if { 0x69, 0x66 }
30	Skill bitfield in order of least significant bit

Skill offset map

Class	Offset
Amazon	6
Sorceress	36
Necromancer	66
Paladin	96
Barbarian	126
Druid	221
Assassin	251

Items

Player, Player Corpse, Mercenary and Iron Golem items are stored in lists described by this Layout:

Byte	Length	Desc
0	2	JM { 0x4A, 0x4D }
2	2	Item Count. Does not include any items occupying sockets in another item
4	0+	N items, where N is the item count given above + socketed items.
	4+	Coprse Information
	10	71 - 89 only, Mercenary ID
	2+	Expansion only, Mercenary Information
	3+	Expansion only, Iron Golem Information

Coprse Information

Byte	Length	Desc
0	2	JM { 0x4A, 0x4D }
2	2	1 if player is dead and has items on a corpse, otherwise 0
4	0+	If player is dead and has items on a corpse, Coprse Items

Coprse Items

Byte	Length	Desc
0	4	Unknown
4	4	X location of corpse
8	4	Y location of corpse
12	2	JM { 0x4A, 0x4D }
14	2	Item Count. Does not include any items occupying sockets in another item
16	0+	N items, where N is the item count given above + socketed items.

Mercenary Information

Byte	Length	Desc
0	2	jf { 0x6A, 0x66 }
2	0+	If merceneray is hired, Mercenary Items

Mercenary Items

Byte	Length	Desc
0	2	JM { 0x4A, 0x4D }
2	2	Item Count. Does not include any items occupying sockets in another item
4	0+	N items, where N is the item count given above + socketed items.

Pre-Expansion Mercenary Information

Byte	Length	Desc
0	2	JM { 0x4A, 0x4D }
2	8	Mercenary id or 0 if there is no mercenary

Iron Golem Information

Byte	Length	Desc
0	2	kf { 0x6B, 0x66 }
2	1	1 if player has an Iron Golem, otherwise 0
3	0+	If player has an Iron Golem, a sigle item

Single Item Layout

Each item starts with a basic 14-byte structure. Many fields in this structure are not "byte-aligned" and are described by their bit position and sizes. If item is socketed, then following the item are the socketed items.

Bit 71 - 96	Bit	Size	Desc
0		16	JM { 0x4A, 0x4D } (separate from the list header)
16	0	4	? 0x00
20	4	1	Identified
21	5	3	? 0x00
24	8	1	? Broken
25	9	2	? 0x00
27	11	1	Socketed (If socketed, then following this item are any items occuping those sockets)
28	12	1	? 0x00
29	13	1	Picked up since last save
30	14	2	? 0x00
32	16	1	Ear, 0x01 always for version 71 with 26 bytes, always ? 0x00 for Version 71 with 15 and 31 bytes
33	17	1	Starter Gear
34	18	1	? 0x00
35	19	2	? 0x03 for version 71 with 15, 26 or 31 bytes, otherwise 0x00
37	21	1	Compact, 0x01 always for version 71 with 15 bytes, ? 0x00 always for version 71 with 27 bytes
38	22	1	Ethereal
39	23	1	? 0x01 for versions 87+, otherwise 0x00
40	24	1	Personalized, ? 0x00 always for version 71
41	25	1	? 0x00
42	26	1	Runeword, ? 0x00 always for version 71
43	27	5	? 0x00

Ear Item:

Bit 71 26 bytes	Bit 71 27 bytes	Size	Desc
48	48	5	? 0x00
53		10	? 0x00
	53	10	0x13B always, Ear Type code
63	63	3	? 0x00
66	66	5	Column
71	71	2	Row
73	73	1	? 0x00
74		3	Stash
77		5	? 0x00
82	74	3	Opponent Class
	77	8	? 0x00
	85	3	Stash
	88	4	? 0x00
85	92	8	Opponent Level
93	100	105	Opponent Name
198		10	? 0x00
	205	11	? 0x00

Bit 87 - 96	Bit	Size	Desc
	32	3	? 0x00
48		10	? 0x00
58	35	3	Parent, always 0x00
61	38	4	Equipped, always 0x00
65	42	4	Column
69	46	3	Row
72	49	1	? 0x00
73	50	3	Stash
76	53	3	Opponent Class
79	56	7	Opponent Level
	63	120	Opponent Name
86		105	Opponent Name
	183	1	? 0x00
191		7	? 0x00

Simple Item:

Bit 71 15 bytes	Bit 71 27 bytes	Size	Desc
48		18	? 0x00
	48	20	? 0x00
66		5	Column if socketed, then 0x00 always if stored in belt, then 4 bits used, 2 for belt row and 2 for belt column
	68	10	Type code, 10 bit integer
71		3	Row if socketed, 3 bits used otherwise 2 bits, 0x00 always if stored in belt.
74		3	Stash
77		3	? 0x00
	78	1	0x01 socket or belt if potion
	79	42	? 0x00
80		2	? 0x03
82		30	Type code (3 letters)
112		8	? 0x00 to pad to 120 bits
	121	5	Column if socketed, then 0x00 always if stored in belt, then 4 bits used, 2 for belt row and 2 for belt column
	126	3	Row, if socketed, 3 bits used otherwise 2 bits, 0x00 always if stored in belt.
	127	76	? 0x00 to pad to 120 bits
	203	8	Parent if bits 4-8 are 0, then stored and bits 0-3 are for Stash
	211	5	? 0x00 to pad to 216 bits

Bit 87 - 96	Bit	Size	Desc
	32	3	? 0x00
48		10	? 0x00
58	35	3	Parent
61	38	4	Equipped, always 0x00
65	42	4	Column
69	46	3	Row
72	49	1	? 0x00
73	50	3	Stash
	53	8-30	Type code (3 letters)
76		30	Type code (3 letters)
106	61 - 83	1 or 3	if quest item, then 2 bits for quest and 1 bit for num sockets, otherwise 1 bit for sockets
	62 - 86	0-4	? 0x00 to pad to 64 or 88 bits
107 or 109		3-5	? 0x00 to pad to 112 bits

Gold Item (unused):

Bit 71 27 bytes	Bit 71 31 bytes	Size	Desc
	48	10	? 0x00
	58	30	Type code (3 letters)
48	90	16	? 0x00
64		4	? 0x00
68		10	Type code, 10 bit integer
78		3	? 0x00
	106	7	? 0x00
81	113	4	? 0x00
85	117	12	12 bit integer holding gold amount
97	129	24	? 0x00
121	153	5	Column
126	158	3	Row
129	161	72	? 0x00
203	235	8	Parent if bits 4-8 are 0, then stored and bits 0-3 are for Stash
211	243	5	? 0x00 to pad to 216/248 bits

Bit 87 - 96	Bit	Size	Desc
	32	3	? 0x00
48		10	? 0x00
58	35	3	Parent
61	38	4	Equipped, always 0x00
65	42	4	Column
69	46	3	Row
72	49	1	? 0x00
73	50	3	Stash
	53	8-30	Type code (3 letters)
76		30	Type code (3 letters)
	61 - 83	1-5	? 0x00 to pad to 64 or 88 bits
106		6	? 0x00 to pad to 112 bits

Extended items:

Bit 71 27 bytes	Bit 71 31 bytes	Size	Desc
	48	10	? 0x00
	58	30	Type code (3 letters)
48	90	4	Equipped
52	94	1	? 0x00
53	95	3	number of socketed items
56	98	8	Item Level
64		4	? 0x00
68		10	Type code, 10 bit integer
78		3	? 0x00
	106	7	? 0x00
81	113	4	Quality
85	117	9	number items stacked
94	126	11	? 0x00
105	137	16	Durability
121	153	5	Column if socketed, then 0x00 always if stored in belt, then 4 bits used, 2 for belt row and 2 for belt column
126	158	3	Row, if socketed, then 3 bits used otherwise 2 bits, 0x00 always if stored in belt.
129	161	8	Set ID, Unique ID, or 0x00 if not part of a Set or Unique
139	171	32	DWA
171	203	32	DWB
203	235	8	Parent if bits 4-8 are 0, then stored and bits 0-3 are for Stash
211	243	5	? 0x00 to pad to 216/248 bits

Bit 87 - 96	Bit	Size	Desc
	32	3	? 0x00
48		10	? 0x00
58	35	3	Parent
61	38	4	Equipped, always 0x00
65	42	4	Column
69	46	3	Row
72	49	1	? 0x00
73	50	3	Stash
	53	8-30	Type code (3 letters)
76		30	Type code (3 letters)
106		2	? 0x00
108	61 - 83		Extended Item Data

Extended Item Data

If the item is marked as Compact (bit 37 is set) no extended item information will exist and the item is finished.

Items with extended information store bits based on information in the item header. For example, an item marked as Socketed will store an extra 3-bit integer encoding how many sockets the item has.

Bit 87 - 96	Bit	Size	Desc
108	61 - 83	3	if quest item, then 2 bits for quest difficulty and 1 bit for number of occupied sockets, otherwise 3 bits for number of occupied sockets. If there are occupied sockets, then following this item will be the items contained in those sockets.
111	64 - 86	4	Quality
115	68 - 90	1+	Custom Graphics
116 - 119	69 - 94	1+	Class Specific
		0+	Quality Attributes
		0+	16 bits exist only if a item is a runeword. The first 12 bits is the runeword Id from Runes.txt. Runeword Mods will exist at the the end of the item data.
		0+	Character Name exists only for personalize items. For versions 87 - 97, 105 bits, otherwise 120 bits
		0+	5 bits exist only if a tome indicating the spell Id (0 - Tome of Town Portal, 1 - Tome of Identify )
		0+	10 bits exist only if a body part item (unused in game) indicating the monster Id from monstats.txt
		1+	Realm Data flag, if first bit is set then Realm Data bits follow. For Miscellaneous items, Gems, Rings, Amultes, Charms and Runes, 96 bits follow for versions 87 - 96, otherwise 128 bits follow. For all other items 3 bits follow.
		0+	For Armor, the defense rating. Versions 87 - 92, 10 bits, otherwise 11 bits
		0+	For Armor or Weapons, the max durability value (8 bits). If max durability is not zero, then current durablilty value follows. Versions 87 - 92, 8 bits follow, otherwise 9 bits follow
		0+	For Stackable items, the quanity of items stacked (9 bits)
		0+	For Set items, the set bonus bits indicated how many Set Mods exists (5 bits)
		0+	If the item is socketed, it will contain 4 bits of data which are the number of total sockets the item has, regardless of how many are occupied by an item.
		9+	Mods

Custom Graphics

Custom graphics are denoted by a single bit, which if set means a 3-bit number for the graphic index follows. If the bit is not set the 3-bits are not present.

Bit	Size	Desc
0	1	Item has custom graphics
1	3	Alternate graphic index

Class Specific

Class items like Barbarian helms or Amazon bows have special properties specific to those kinds of items. If the first bit is empty the remaining 11 bits will not be present.

Bit	Size	Desc
0	1	Item has class specific data
1	11	Class specific bits

Quality

Item quality is encoded as a 4-bit integer. For version 87+, except for Normal Quality, the other quality values have Quality Attributes of a certian size that come after the Class Specific bits.

Value	Size	Desc
1	3	Inferior
2	0/12	Normal (12 bits if it is a Charm, otherwise 0)
3	3	Superior (bits that follow are set to 0)
4	22	Magically Enhanced
5	12	Part of a Set (bit that follow are the Set Id from the Sets.txt file)
6	22+	Rare
7	12	Unique (bits that follow are the Unique Id from the UniqueItems.txt file)
8	22+	Craft
9	22+	Tempered (Not Enabled)

Inferior

Inferior items have a 3-bit integer follow the quality value.

Value	Desc
0	Crude
1	Cracked
2	Damaged
3	Low Quality

Magically Enhanced

Magically enhanced items have two 11-bit integers that follow each other.

Size	Desc
11	Prefix Id from the MagicPrefix.txt file
11	Suffix Id from the MagicSuffix.txt file

Rare, Craft or Tempered

Tempered items are not enabled, however these three Quality values have the same structure and contain a name with two words and between 3 and 6 affixes. The name values have no affect on the item's magical properties.

Size	Desc
8	First word of name from the RarePrefix.txt file
8	Second word of name from the RareSuffix.txt file
1 - 12	if first bit is set, then ll bits follow for the first Prefix Id from the MagicPrefix.txt file
1 - 12	if first bit is set, then ll bits follow for the first Suffix Id from the MagicSuffix.txt file
1 - 12	if first bit is set, then ll bits follow for the second Prefix Id from the MagicPrefix.txt file
1 - 12	if first bit is set, then ll bits follow for the second Suffix Id from the MagicSuffix.txt file
1 - 12	if first bit is set, then ll bits follow for the third Prefix Id from the MagicPrefix.txt file
1 - 12	if first bit is set, then ll bits follow for the third Suffix Id from the MagicSuffix.txt file

Mods

After each item is a list of mods. The list is a series of key value pairs where the key is a 9-bit number and the value depends on the key. The list ends when key 511 (0x1ff) is found which is all 9-bits being set.

Using the file ItemStatCost.txt as a tab-delimited CSV file you can extract the ID column which maps to the 9-bit keys. The columns Save Bits and Param Bits describe how large the mod is.

The only exception is min-max style modifiers which use the next row in the CSV to store the "max" portion of the mod. The bit sizes of these two can be different and you should sum them to get the total size.

If the item is a set item, then there may follow upto 5 more list of mods containg the set magical properties.

If the item has a runeword set, then there is one more list of mods holding the magical properties of the applied runeword.

Parent

All items are located somewhere and have a "parent" which can be another item, such as when inserting a jewel.

Value	Desc
0	Stored
1	Equipped
2	Belt
4	Cursor
6	Item

For items that are "stored" a 3-bit integer encoded starting at bit 73 describes where to store the item:

Value	Desc
1	Inventory
4	Horadric Cube
5	Stash

Equipped

Items that are equipped describe their slot:

Value	Slot
1	Helmet
2	Amulet
3	Armor
4	Weapon (Right)
5	Weapon (Left)
6	Ring (Right)
7	Ring (Left)
8	Belt
9	Boots
10	Gloves
11	Alternate Weapon (Right)
12	Alternate Weapon (Left)