MSB map layouts

FromSoftware engineWorld and streamingApplies toSekiro Elden Ring

An MSB describes a map’s models and their occurrences, regions and events. A model entry names a resource; a part places it, so several parts can share one model. Parts also carry entity IDs used by event scripts. Observed

Sekiro uses the MSBS generation and Elden Ring uses MSBE. The ordered section names identify the generation; section revision numbers alone do not, because revisions can differ while the record layout stays the same. Observed

Sections

Order	MSBS	MSBE	Confidence
1	`MODEL_PARAM_ST`	Same	Observed · Sekiro Proven · Elden Ring
2	`EVENT_PARAM_ST`	Same	Observed · Sekiro Proven · Elden Ring
3	`POINT_PARAM_ST` (regions)	Same	Observed · Sekiro Proven · Elden Ring
4	`ROUTE_PARAM_ST`	Same	Observed · Sekiro Proven · Elden Ring
5	`LAYER_PARAM_ST` (empty in the examined layouts)	Same	Observed · Sekiro Proven · Elden Ring
6	`PARTS_PARAM_ST`	Same	Observed · Sekiro Proven · Elden Ring
7	`MAPSTUDIO_PARTS_POSE_ST` (empty in the examined layouts)	Absent	Observed · Sekiro Proven · Elden Ring
8	`MAPSTUDIO_BONE_NAME_STRING` (empty in the examined layouts)	Absent	Observed · Sekiro Proven · Elden Ring

The file begins with MSB and a 16-byte header; the first section starts at 16. Section pointers are absolute, whereas pointers inside a part or model record are relative to that record. Strings are NUL-terminated UTF-16. Observed

Section revisions

A file stores one revision, repeated in every section header of its chain; the two empty trailing sections of a Sekiro file store 0. This holds in all 10 Sekiro and all 935 Elden Ring MSBs of the installs examined (the Elden Ring install is the base game without the expansion archive). Proven

Game	Revisions stored (files)	Confidence
Sekiro	35 (9 maps), 33 (`m89_00_00_99`)	Proven · Sekiro
Elden Ring	73 (547), 74 (160), 57 (46), 51 (39), 69 (30), 64 (30), 71 (22), 65 (21), 63 (20), 66 (18), 46 (1), 70 (1)	Proven · Elden Ring

Every Elden Ring file reads with the one six-section layout whatever its revision, so a reader that accepts only 73 refuses 388 of the 935 files. Proven · Elden Ring Within m60 the revision varies from tile to tile (73 on 460 tiles, 74 on 153, and eight further revisions on 18 to 46 tiles each). Proven · Elden Ring

Section header and pointer table (Sekiro)variableSekiro100% known

Little-endian; offsets are absolute from the MSB start.

ProvenObservedSourcedInferredUnknownNot described

Offset	Size	Type	Field	Confidence	Notes
0x0	4	u32	section revision	Observed
0x4	4	u32	pointer count	Observed	Record count plus one
0x8	8	u64	section name offset	Observed
0x10	8 × record count	u64[]	record offsets	Observed
after record offsets	8	u64	next section offset	Observed	Zero terminates the chain

Section header and pointer table (Elden Ring)variableElden Ring100% known

Little-endian; offsets are absolute from the MSB start.

ProvenObservedSourcedInferredUnknownNot described

Offset	Size	Type	Field	Confidence	Notes
0x0	4	u32	section revision	Proven
0x4	4	u32	pointer count	Proven	Record count plus one
0x8	8	u64	section name offset	Proven
0x10	8 × record count	u64[]	record offsets	Proven
after record offsets	8	u64	next section offset	Proven	Zero terminates the chain

Section layout

In every file of both installs a section is: its header (revision, pointer count, name offset), the table of record offsets ending in the next section’s offset, the section’s name directly after the table, zero bytes to the next multiple of 8, and its records back to back. A record runs to the next record’s offset, the last record of a section to the next section’s start, so the padding after a record belongs to it, and every record of both installs is a multiple of 8 bytes long. An empty section has the table’s single slot, its name and the padding, and the next section follows at once. The last section’s next-section slot is 0. Proven · every MSB of both installs Laying the sections out again from their revisions, names and records this way reproduces all 10 Sekiro and all 887 distinct Elden Ring files byte for byte. Proven · an independent writer over every MSB of both installs

Parts

Ashina Castle’s map-piece and object names, model references, positions, rotations and scales agree bit for bit with an independent SoulsFormats decode. That comparison does not cover the other Sekiro part kinds. Observed · Sekiro The whole-install Elden Ring comparison covers all 935 MSBs, all 457,108 parts of every kind and all 227 spawn points, with no refusals. Model names, part transforms, IDs, shadow controls, hit filters and spawn-point values agree with SoulsFormatsNEXT. Proven · Elden Ring

MSBS part header — selected fields160 bytesSekiro53% known

Offsets within records are relative to the record start. Unlisted fields are not described here.

ProvenObservedSourcedInferredUnknownNot described

Offset	Size	Type	Field	Confidence	Notes
0x0	8	u64	name offset	Observed
0x8	4	u32	part kind	Observed
0x10	4	i32	model index	Observed	-1 names no model
0x18	8	u64	resource path offset	Sourced
0x20	12	f32[3]	position	Observed
0x2C	12	f32[3]	rotation in degrees	Observed
0x38	12	f32[3]	scale	Observed
0x60	8	u64	entity data offset	Observed	Entity block occupies 0x54 bytes
0x68	8	u64	type data offset	Observed
0x70	8	u64	graphics configuration offset	Observed
0x78	8	u64	scene configuration offset	Observed

MSBE part header — selected fields192 bytesElden Ring44% known

Unlisted fields are not described here; record-relative offsets.

ProvenObservedSourcedInferredUnknownNot described

Offset	Size	Type	Field	Confidence	Notes
0x0	8	u64	name offset	Proven
0xC	4	u32	part kind	Proven
0x14	4	i32	model index	Proven	-1 names no model
0x18	8	u64	resource path offset	Sourced
0x20	12	f32[3]	position	Proven
0x2C	12	f32[3]	rotation in degrees	Proven
0x38	12	f32[3]	scale	Proven
0x60	8	u64	entity data offset	Proven	Entity block occupies 0x40 bytes
0x68	8	u64	type data offset	Proven
0x70	8	u64	graphics configuration offset	Proven
0x78	8	u64	scene configuration offset	Proven

Within entity data, the entity ID is at +0 and eight group IDs start at +0x1c. Enemy type data stores the NPC row ID at +12. Sourced · SoulsFormatsNEXT

Kind 0 is a map piece, 2 an enemy, 4 a player, 5 collision, 10 a dummy enemy and 11 connecting collision. Sourced · SoulsFormatsNEXT only in Sekiro Kind 1 is an object and 9 a dummy object. Sourced · Sekiro · SoulsFormatsNEXT only in Elden Ring Kind 13 is an asset and 9 a dummy asset. Sourced · Elden Ring · SoulsFormatsNEXT

An entity ID of 0 or -1 names no entity. A positive group ID lets an event address all parts in that group. Observed

Part kinds present

Over all parts of the installs, only the kinds above occur; no part has kind 6 (the navmesh kind of earlier games). Model records have kind 0, 1, 2, 4 or 5 in Sekiro and 0, 2, 4, 5 or 10 in Elden Ring (4,335 / 1,266 / 284 / 4 / 1,353 Sekiro records of those kinds; 4,958 / 4,475 / 189 / 3,351 / 40,530 Elden Ring records). Proven

Kind	Sekiro parts	Elden Ring parts
0 map piece	40,970	4,522
1 object	10,538	n/a
2 enemy	1,557	16,776
4 player	70	722
5 collision	1,304	3,266
9 dummy object / dummy asset	125	2,661
10 dummy enemy	206	7,108
11 connecting collision	582	800
13 asset	n/a	421,253
Total	55,352	457,108

The counts cover the 10 Sekiro and 935 Elden Ring MSBs of the installs. Proven

Model records

A model record is 40 bytes of header before its strings, in both games (the name offset is 40 in all 7,242 Sekiro and 53,503 Elden Ring records). Its u32 at +24 is the number of parts that name the model: it equals the count of parts whose model index is that record in every model record of both installs. A file’s parts reference no model index outside its model section, apart from the -1 of 4 Elden Ring files. Proven

Payload slots

The part header’s payload slots (eleven u64 from +80 in Elden Ring, seven in Sekiro) hold offsets of blocks, 0 for none. The size below is the distance from a block to the next higher offset or the record’s end, so it includes alignment padding. Proven

Slot	Block	Size (Sekiro / Elden Ring)	Present on
`+80`	draw and display groups	388 / 392	Elden Ring: every kind. Sekiro: map piece, object, enemy, collision
`+88`	second display-group block	72 / 72	Collision and connecting collision in both games; Elden Ring assets
`+96`	entity data	84 (88 on player, dummy and connecting-collision kinds) / 64	Every kind
`+104`	type data	per kind	Every kind
`+112`	graphics configuration	32 / 32	Every kind except player and connecting collision
`+120`	scene configuration	80 / 80	Collision only
`+128`	Sekiro: unnamed; Elden Ring: grass configuration	32 / 32	Sekiro map pieces only; Elden Ring map pieces and assets
`+136`, `+152`	Elden Ring: unnamed; `+152` is the tile-load configuration	32	Elden Ring: every kind
`+144`, `+160`	Elden Ring: unnamed	32	Elden Ring: `+144` map pieces and assets; `+160` map pieces, collisions, connecting collisions and assets

Type-data sizes (Sekiro / Elden Ring): map piece 8 / 8; object 40 / n/a; enemy and dummy enemy 192 / 192; player 16 / 16; collision 96 / 80; dummy object or asset 40 / 32; connecting collision 16 / 16; asset n/a / 392. Proven

Asset effects (Elden Ring)

An asset part’s type data stores at +0x1c a signed 16-bit word, the relative id of the row of AssetModelSfxParam its effects come from: row (nnn x 1000 + mmm) x 1000 + id for the asset model AEGnnn_mmm (see model effect params); -1 names none. Of the 421,253 asset parts of AEGnnn_mmm models, 409,246 store -1, 11,533 name an existing row and 474 name an absent one. Of every 16-bit word of the type data, this is the only one whose non-negative values name an existing row for more than a thousand parts (4,100 positive values name a row and 16 do not; the next best word names one for 966 parts and misses 69,758). Observed · Elden Ring Sekiro’s object part has no such field. Observed · Sekiro

Collision parts

A collision part’s type data starts with a hit-filter byte. The values present, with the community names (Smithbox’s enumerations; both games leave 16, 17, 20, 23 and 24 unnamed):

Value	Name	Sekiro collisions	Elden Ring collisions	Confidence
8	Collide with all characters	1,127	2,095	Proven · Sekiro, Elden Ring · counts Sourced · Sekiro, Elden Ring · Smithbox
9	Collide with camera only	6	27	Proven · Sekiro, Elden Ring · counts Sourced · Sekiro, Elden Ring · Smithbox
11	Collide with non-player characters only	14	71	Proven · Sekiro, Elden Ring · counts Sourced · Sekiro, Elden Ring · Smithbox
13	Trigger fall death camera	12	257	Proven · Sekiro, Elden Ring · counts Sourced · Sekiro, Elden Ring · Smithbox
15	Trigger instant death	13	258	Proven · Sekiro, Elden Ring · counts Sourced · Sekiro, Elden Ring · Smithbox
16	unnamed	19	187	Proven · Sekiro, Elden Ring · counts
17	unnamed	4	92	Proven · Sekiro, Elden Ring · counts
19	Collide with non-player characters only (Sekiro enumeration), unnamed (Elden Ring)	9	38	Proven · Sekiro, Elden Ring · counts Sourced · Sekiro · Smithbox
20	unnamed	0	10	Proven · Sekiro, Elden Ring · counts
22	Block all fall damage (Sekiro enumeration), unnamed (Elden Ring)	17	210	Proven · Sekiro, Elden Ring · counts Sourced · Sekiro · Smithbox
23, 24, 29	unnamed	0	10, 3, 8	Proven · Elden Ring · counts
25, 26, 27, 28	absent from the community enumerations	6, 2, 64, 11	0	Proven · Sekiro · counts

The counts are over all 1,304 Sekiro and 3,266 Elden Ring collision parts. Values 0 to 7, 14 and 21 (named in the Sekiro enumeration) do not occur in either install. Proven

In Elden Ring the collision type data holds two more bytes read from the data: +0x35 is 255 on 3,225 of 3,266 collisions and otherwise 0, 1, 2, 3, 21, 31 or 41 (41 collisions, all in m60 tiles), and +0x36 is 0 on 1,877 and 1 on 1,389. How +0x35 selects a graphics-parameter file is under graphics parameters. Proven · Elden Ring

Entity IDs and groups

Entity IDs and group IDs follow a numbering per area, in the decimal digits of the ID. Counted over every positive entity ID in the installs’ MSBs (part IDs, the eight group IDs of each part, region IDs and the entity ID in each event’s base data), n being a number below 10,000:

Game and kind of map	Form	Parts	Part groups	Regions	Events	Confidence
Sekiro, all maps but `_99`	`area × 10^5 + block × 10^4 + n`	2,616 of 2,619	2,783 of 2,783	1,787 of 1,871	203 of 213	Observed · Sekiro
Elden Ring, legacy dungeons and other non-overworld maps	`area × 10^6 + block × 10^4 + n`	6,241 of 6,256	6,198 of 6,204	3,106 of 3,425	239 of 240	Observed · Elden Ring
Elden Ring, `m60` tiles	`10^9 + X × 10^6 + Z × 10^4 + n` for tile `m60_X_Z_*`	5,077 of 5,808	2,741 of 3,759	1,778 of 2,304	125 of 136	Observed · Elden Ring

“Of” counts the positive IDs of that kind in those maps; the others are small numbers (group IDs 7 and 8, region IDs 1 and 2) or follow the numbering of another block (a m10_00 region with an ID of the m10_01 form). The Elden Ring forms are also the forms of the event flags that the map’s own scripts set (see EMEVD).

Regions and events

Regions combine a type, a shape and a placement. Sourced · SoulsFormatsNEXT

Region record header — selected common fields96 (Sekiro), 104 (Elden Ring)15% known

Region-record-relative offsets; type-specific payloads differ. The first string (the name) starts at the header's end.

ProvenObservedSourcedInferredUnknownNot described

Offset	Size	Type	Field	Confidence	Games	Notes
0x0	8	u64	name offset	Sourced		Equals the header size (96 or 104) in all 45,121 regions
0x8	4	u32	region type	Sourced
0xC	4	u32	index among the regions of the same type	Proven		Counts from 0 in file order; equals the per-type counter in all 45,121 regions
0x10	4	u32	shape type	Sourced
0x14	12	f32[3]	position	Sourced
0x20	12	f32[3]	rotation in degrees	Sourced
0x2C	4	u32	region number	Proven		Unique within the file in all 945 files; not the record index (equal to it in 391 of 45,121 regions)
0x48	8	u64	shape data offset	Sourced
0x50	8	u64	entity data offset	Sourced
0x58	8	u64	type data offset	Sourced		0 in all 6,872 Elden Ring regions of type 0xffffffff and in 37 regions of other types
0x60	8	u64	extra data offset	Proven	Elden Ring	Non-zero in all 36,409 regions; the block it names is described below

Event record header — selected common fields40 (Sekiro), 48 (Elden Ring)33% known

Event-record-relative offsets; type-specific payloads differ. The name string starts at the header's end.

ProvenObservedSourcedInferredUnknownNot described

Offset	Size	Type	Field	Confidence	Games	Notes
0x0	8	u64	name offset	Sourced		Equals the header size (40 or 48) in all 9,211 events
0x8	4	u32	event number	Proven		Unique within the file in all 945 files; not the record index (equal to it in 367 of 9,211 events); densely 0..n-1 in 731 of 945 files
0xC	4	u32	event type	Sourced
0x10	4	u32	index among the events of the same type	Proven		Equals the per-type counter in 9,209 of 9,211 events; the other two have type 0xffffffff
0x18	8	u64	base data offset	Sourced		Part index, region index and entity ID (16 bytes)
0x20	8	u64	type data offset	Sourced		0 for events of type 0xffffffff, and for Sekiro type 22
0x28	8	u64	extra data offset	Proven	Elden Ring	Non-zero in all 7,585 events; the block it names is described below

The event and region sections of every Elden Ring file are sorted by type, as are the event sections of all 10 Sekiro files (the Sekiro region sections of 3 of the 10). The number at +8 of an event and the number at +44 of a region are file-wide identifiers that keep their values when records are removed: they are unique in every file but dense (a permutation of 0..n-1) in only 731 of the 945 event sections and 419 of the region sections, and they are in section order in 597 of the event sections of the Elden Ring files. They are neither the record index nor the per-type index. Proven

Extra block (Elden Ring)

only in Elden Ring Every region and event ends with a 32-byte block that its extra data offset names. It is the last thing in the record: the block ends at the record’s end in 23,517 regions and 7,571 events, and 4 zero bytes of alignment follow it in the other 12,892 regions and 14 events. Proven

Region and event extra block32 bytesElden Ring63% known

ProvenObservedSourcedInferredUnknownNot described

Offset	Size	Type	Field	Confidence	Notes
0x0	4	u32	map word	Proven	0xffffffff in 35,784 of 36,409 regions and 7,454 of 7,585 events; otherwise a map word (area in the top byte)
0x4	4	u32	unknown	Unknown	0 with a default map word; 13 in all 756 records with a map word
0x8	4	u32	unknown	Unknown	0 in every region and event but one (2)
0xC	4	i32	unknown	Unknown	-1 with a default map word; otherwise a non-negative number (226 distinct values, up to 9,081) whose meaning is not established
0x10	16	u8[16] = 0	padding	Proven

The records with a map word are the 625 regions and 131 events of 46 overworld tiles of levels 1 and 2: 17 _01 tiles, 26 _02 tiles and the alternate tiles m60_*_11 (2) and m60_*_12 (1). Proven How the word is read is under map words.

Sekiro has no extra block or pointer: its region header ends at +96, its event header at +40, and the name string follows. Proven · Sekiro A reader that takes a region’s or event’s type data as “from the type-data offset to the record’s end” in Elden Ring therefore includes the 32-byte block (and up to 4 padding bytes) in it.

Effect regions (type 5)

An SFX region’s type data names the effect it spawns (an FXR file by id) and whether the effect starts disabled until an event script enables it. The word that holds the flag is SoulsFormats’ StartDisabled (an integer); the files store only 0 and 1 in Elden Ring’s, and in Sekiro’s 0, 1, 256 and 257, so its low byte is read as the flag.

SFX region type data8 (Elden Ring, before the extra block), 24 or 28 (Sekiro)67% known

ProvenObservedSourcedInferredUnknownNot described

Offset	Size	Type	Field	Confidence	Games	Notes
0x0	4	i32	effect id	Proven		The number of an FXR file; 1,872 Sekiro and 1,523 Elden Ring regions
0x4	4	u32	start disabled	Sourced	Elden Ring	0 or 1 in all 1,523 regions (17 are 1)
0x4	4	i32	unnamed	Unknown	Sekiro	SoulsFormats' UnkT04: -1 in 1,868 regions, 0x00110440 in 4
0x8	12	i32[3] = -1	padding	Proven	Sekiro
0x14	4	u32	start disabled	Sourced	Sekiro	Low byte 0 or 1 (54 of 1,872 regions are 1); the second byte is 1 in 13 regions, not understood; the two high bytes are 0

Every SFX region of both installs has a flag byte of 0 or 1 and, in Elden Ring, zero bytes after it in its word. Proven · every region of type 5 of both installs

Wind regions (type 6)

A WindSFX region’s type data also starts with an effect id, of an effect whose action is a WindForce (parameters); the Stormveil region 【GD_環境風_突風12-5m】_808003_1001 (a box 120.307 × 110.863 × 72.456, turned 36.404° about y) stores [808003, 289, −1.0]. Observed · Elden Ring

only in Elden Ring The game builds the wind regions with the SFX regions when a world block is set up, and every frame spawns or removes their effects by a global flag, a 256-bit mask and two enable bits, with no test of the player’s position. Observed · Elden Ring · read from the code of 1.17.3 A loaded region keeps the file’s record layout, with its offsets turned into pointers and its rotation into radians, f32(degrees) × f32(π / 180) (0x3C8EFA35). The region’s matrix is the rotation (from the C runtime’s sinf and cosf of those radians) times the translation to its position; the effect is spawned at that matrix times the world block’s offset (frames). A box region’s area has the same rows, scaled by half its width, height and depth (the box’s third value being the height), and its centre is the spawn position plus half the height in y. Observed · Elden Ring · the game’s own code run from a memory image of 1.17.3, one region With the block offset (88, −16, −16), the spawn matrix equals the running force field’s transform bit for bit, and the box centre’s y the field origin’s y. Observed · Elden Ring · one region, one recording For a turn about y alone the rotation’s rows are (cos, 0, −sin), (0, 1, 0) and (sin, 0, cos), and the field blows along the third row. All twelve wind regions of Stormveil’s layout resolve to a field this way, and the recorded cloth stood inside exactly one region’s box. Observed · Elden Ring · one recording Whether the box containing the cloth is how the game picks the field in general is not established, and the x and z of the field’s origin are not read from the code. Unknown · Elden Ring

Shape variants include points, circles, spheres, cylinders, rectangles, boxes and composites; a shape and a region’s purpose are different fields. Sourced · SoulsFormatsNEXT

Shape code	Payload	Confidence
`0xffffffff`	No shape	Sourced · SoulsFormatsNEXT
0	Point, no dimensions	Sourced · SoulsFormatsNEXT
1 / 2	Circle / sphere, one radius float	Sourced · SoulsFormatsNEXT
3	Cylinder, radius then height	Sourced · SoulsFormatsNEXT
4	Rectangle, width then depth	Sourced · SoulsFormatsNEXT
5	Box, width then depth then height	Sourced · SoulsFormatsNEXT
6	Composite child-region records	Sourced · SoulsFormatsNEXT

Region type 8 identifies spawn points in both generations. Sourced · SoulsFormatsNEXT Sekiro’s event type 9 is MapOffset; MSBE has no corresponding MapOffset event. See coordinate frames. Observed

How do all region and event types behave?

Community definitions name many types, but a name alone does not establish activation, priority or runtime lifetime. Type-specific bytes need a separate interpretation for each type and game.