M2

M2 files (also called MDX) contain model objects. Each M2 file describes the vertices, faces, materials, texture names, animations and properties of one model. M2 files don't have a chunked format like most other WoW formats.

Models are used for doodads (decoration objects), players, monsters and really everything in the game except for Terrain and WMOs.

This file describes their structure in the second expansion "Wrath of the Lich King". It is up to date for build 8820 and most likely following ones. It has been made by Xayo and schlumpf. All structures have been overlooked by schlumpf. Enjoy it.

--schlumpf_ 00:50, 23 August 2008 (CEST)

Header

The header has mostly the layout of number-offset pairs, containing the number of a particular record in the file, and the offset. These appear at fixed places in the header. Record sizes are not specified in the file.

	Offset	Type	Name	Description
	0x000	char[4]	Magic	"MD20"
	0x004	uint32	Version	0x80100000 (first digit of the build the format was last updated)
	0x008	uint32	lName	Length of the model's name
	0x00C	uint32	ofsName	Offset to the name
	0x010	uint32	GlobalModelFlags	(0,1,3 seen), connected to field 4 of CreatureModelData.dbc?
	0x014	uint32	nGlobalSequences
	0x018	uint32	ofsGlobalSequences	A list of timestamps.
	0x01C	uint32	nAnimations
	0x020	uint32	ofsAnimations	Information about the animations in the model.
	0x024	uint32	nAnimationLookup
	0x028	uint32	ofsAnimationLookup	Mapping of global IDs to the entries in the Animation sequences block.
	0x02C	uint32	nBones
	0x030	uint32	ofsBones	Information about the bones in this model.
	0x034	uint32	nKeyBoneLookup
	0x038	uint32	ofsKeyBoneLookup	Lookup table for key skeletal bones.
	0x03C	uint32	nVertices
	0x040	uint32	ofsVertices	Vertices of the model.
	0x044	uint32	nViews	Views (LOD) are now in .skins.
	0x048	uint32	nColors
	0x04C	uint32	ofsColors	Color definitions.
	0x050	uint32	nTextures
	0x054	uint32	ofsTextures	Textures of this model. Now .skins?
	0x058	uint32	nTransparency
	0x05C	uint32	ofsTransparency	Transparency of textures.
	0x060	uint32	nTextureanimations
	0x064	uint32	ofsTextureanimations
	0x068	uint32	nTexReplace
	0x06C	uint32	ofsTexReplace	Replaceable Textures.
	0x070	uint32	nRenderFlags
	0x074	uint32	ofsRenderFlags	Blending modes / render flags.
	0x078	uint32	nBoneLookupTable
	0x07C	uint32	ofsBoneLookupTable	A bone lookup table.
	0x080	uint32	nTexLookup
	0x084	uint32	ofsTexLookup	The same for textures.
	0x088	uint32	nTexUnits
	0x08C	uint32	ofsTexUnits	And texture units. Somewhere they have to be too.
	0x090	uint32	nTransLookup
	0x094	uint32	ofsTransLookup	Everything needs its lookup. Here are the transparencies.
	0x098	uint32	nTexAnimLookup
	0x09C	uint32	ofsTexAnimLookup	Wait. Do we have animated Textures? Wasn't ofsTexAnims deleted? oO
	0x0A0	float	theFloats[14]	Noone knows. Meeh, they are here.
	0x0D8	uint32	nBoundingTriangles
	0x0DC	uint32	ofsBoundingTriangles	Our bounding volumes. Similar structure like in the old ofsViews.
	0x0E0	uint32	nBoundingVertices
	0x0E4	uint32	ofsBoundingVertices
	0x0E8	uint32	nBoundingNormals
	0x0EC	uint32	ofsBoundingNormals
	0x0F0	uint32	nAttachments
	0x0F4	uint32	ofsAttachments	Attachments are for weapons etc.
	0x0F8	uint32	nAttachLookup
	0x0FC	uint32	ofsAttachLookup	Of course with a lookup.
	0x100	uint32	nAttachments_2
	0x104	uint32	ofsAttachments_2	And some second block.
	0x108	uint32	nLights
	0x10C	uint32	ofsLights	Lights are mainly used in loginscreens but in wands and some doodads too.
	0x110	uint32	nCameras
	0x114	uint32	ofsCameras	The cameras are present in most models for having a model in the Character-Tab.
	0x118	uint32	nCameraLookup
	0x11C	uint32	ofsCameraLookup	And lookup-time again.
	0x120	uint32	nRibbonEmitters
	0x124	uint32	ofsRibbonEmitters	Things swirling around. See the CoT-entrance for light-trails.
	0x128	uint32	nParticleEmitters
	0x12C	uint32	ofsParticleEmitters	Spells and weapons, doodads and loginscreens use them. Blood dripping of a blade? Particles.

Skeleton and animation

Standard animation block

• Many values that change with time are specified using blocks like the following.

Please see this for information.

If a global sequence is used, it means there is an implicit interpolation range across all values, and a time range from 0 to the proper global sequence timestamp.

If the interpolation type is 0, in some cases that might mean that no animation is given (like for bones), in other cases it means that a single constant data value should be used (like for colors and effect paramters)

Global sequences

• nGlobalSequences 32-bit unsigned integers starting at ofsGlobalSequences.

A list of timestamps that act as upper limits for global sequence ranges.

	Offset	Type	Name	Description
	0x00	uint32	Timestamp	Entry

Animation sequences

• nAnimations 0x40-byte records starting at ofsAnimations.

List of animations present in the model.

	Offset	Type	Name	Description
	0x00	uint16	AnimationID	Animation id in AnimationData.dbc
	0x02	uint16	SubAnimationID	Sub-animation id: Which number in a row of animations this one is.
	0x04	uint32	Length	The length (timestamps) of the animation.
	0x08	float	MovingSpeed	As 2.x says: moving speed for walk/run animations.
	0x0C	uint32	Flags	Most likely. All flags I saw: 0b01101101
	0x10	uint32	Flags 2	Only the first 4 bits are the actual flags. The rest is 1. Seen flags: 0,3,6,7
	0x14	uint32	Unknown 1	These two are connected. Most of the time, they are 0.
	0x16	uint32	Unknown 2	But if there is data in one, there is data in both of them.
	0x1C	uint32	PlaybackSpeed	Values: 0, 50, 100, 150, 200, 250, 300, 350, 500.
	0x20	float	BoundingBox[6]	A Bounding Box made out of 2 vectors.
	0x38	float	Radius	The radius.
	0x3C	int16	NextAnimation	Id of the following animation of this AnimationID, points to an Index or is -1 if none.
	0x3E	uint16	Index	Id in the list of animations.

Animation Lookup

• nAnimationLookup in 16-bit shorts starting at ofsAnimationLookup.

Lookup table for Animations in AnimationData.dbc.

	Offset	Type	Name	Description
	0x00	uint16	AnimationID	Index at ofsAnimations which represents the animation in AnimationData.dbc. -1 if none.

Bones

• nBones records of 0x5C bytes starting at ofsBones.

	Offset	Type	Name	Description
	0x00	int32	AnimationSeq	Index into Animation sequences or -1.
	0x04	uint32	Flags	Only known flags: 8 - billborded and 512 - transformed
	0x08	int16	ParentBone	Parent bone ID or -1 if there is none.
	0x0C	uint16	GeosetID	A geoset for this bone.
	0x10	int32	Unknown	4 bytes that have been in since TBC. Noone knows what they are for.
	0x14	ABlock	Translation	An animationblock for translation. Should be 3*floats.
	0x28	ABlock	Rotation	An animationblock for rotation. Should be 4*shorts, see Quaternion values and 2.x.
	0x3C	ABlock	Scaling	An animationblock for scaling. Should be 3*floats.
	0x50	float	PivotPoint[3]	The pivot point of that bone. Its a vector.

The bone indices in the vertex definitions seem to index into this data.

The billboarding bit is used for various things:

• Light halos around lamps must always face the viewer
• The cannonball stack model (in the Deadmines or Booty Bay), where each cannonball is a crude hemisphere, they always face the viewer to create the illusion of actual cannonballs.

Bone Lookup Table

• nBoneLookupTable 16-bit integers starting at ofsBoneLookupTable. (values: 0 to nBones-1)

Lookup table for bones that transform geometry. Referenced in the various geoset definitions.

	Offset	Type	Name	Description
	0x00	uint16	Bone	Which bone. -1 if there is none.

Key-Bone Lookup

• nKeyBoneLookup 16-bit shorts starting at ofsKeyBoneLookup.

Its a lookup table for key skeletal bones like hands, arms, legs, etc. nKeyBoneLookup is 21 for the most models. At static models it is mostly 1.

	Offset	Type	Name	Description
	0x00	uint16	Bone	Which bone. -1 if there is none.

Geometry and rendering

Vertices

• nVertices entries of 48 bytes per vertex (at ofsVertices)

	Offset	Type	Name	Description
	0x00	float	Position[3]	A vector to the position of the vertex.
	0x0C	uint8	BoneWeight[4]	The vertex weight for 4 bones.
	0x10	uint8	BoneIndices[4]	Which are referenced here.
	0x14	float	Normal[3]	A normal vector.
	0x20	float	TextureCoords[2]	Coordinates for a texture.
	0x28	float	Unknown[2]	Null?

Models, too, use a Z-up coordinate systems, so in order to convert to Y-up, the X, Y, Z values become (X, -Z, Y).

I was wrong. --Hergonan

Views (LOD)

Since there is no ofsViews anymore, this data is now stored in .skin files. More information about them here: M2/WotLK/.skin.

Render flags

• nRenderFlags (uint16, uint16) pairs starting at ofsRenderFlags

	Offset	Description
	0x00	Flags
	0x02	Blending mode

• Flags:

	Flag	Meaning
	0x01	Unlit
	0x02	Unfogged?
	0x04	Two-sided (no backface culling if set)
	0x08	? (probably billboarded)
	0x10	Disable z-buffer?

• Blending mode

	Value	Meaning
	0	Opaque
	1	Alpha testing only
	2	Alpha blending
	3	Additive?
	4	Additive alpha?
	5	Modulate?
	6	Used in the Deeprun Tram subway glass, supposedly (src=dest_color, dest=src_color) (?)

Most of these blend values are taken from the MDL docs, but they sort of work (like additive blending for light shafts and such)

Texture unit lookup table

• nTexUnits 16-bit integers starting at ofsTexUnits.

	Offset	Type	Name	Description
	0x00	int16	Unit	Values are -1, 0 or 1. See below.

For models that use multitexturing, this maps given texture unit numbers into actual texture unit numbers (0 or 1).

Values of -1 seem to mean environment mapping.

One model is of special interest, Creature/KelThuzad/KelThuzad.m2, which is the only one that has an nTexUnits of 3, and has three texture units specified for some of its submeshes. Sure enough, two of those map to 0 and 1, and one maps to -1.

More confusion thanks to my favorite "weird" model, World/Generic/Gnome/Passive Doodads/GnomeMachine/GnomeSubwayGlass.m2, which is the translucent, environment mapped glass tunnel in the Deeprun Tram. It only has a single value in this block, -1, which is used for the single texture layer in both render operations in the model. This and the magic with rendering flags/blend modes make up the neat transparent-reflective glass effect, but confuse me even more about how envmapping and such is handled. (and where it seems to get the bluish color from - is it in the model (no color blocks in this particular model), the wmo, a solid background color, or simply the result of the blending used?)

As a side note, on my (dated) system WoW does every texture unit in a single pass.

Replacable texture lookup

• nTexReplace 16-bit integers starting at ofsTexReplace.

	Offset	Type	Name	Description
	0x00	int16	TextureID	Array indices (0 to n-1).

A reverse lookup table for 'replaced' textures, mapping replacable ids to texture indices or -1. Only goes up to the maximum id used in the model.

Colors and transparency

Colors

• nColors records starting at ofsColors, followed by data referenced in these records.

	Offset	Type	Name	Description
	0x00	ABlock	Color	Three floats. One for each color.
	0x14	ABlock	Alpha	A short for the alpha value. 0 - transparent, 0xFFFF - opaque.

For some swirling portals and volumetric lights, these define vertex colors. Referenced from the Texture Unit blocks in the LOD part. Contains a separate timeline for transparency values. If no animation is used, the given value is constant.

Transparency lookup table

• nTransLookup 16-bit integers starting at ofsTransLookup.

	Offset	Type	Name	Description
	0x00	uint16	TransparencyId	Array indices (0 to n-1).

Contains indices into the Transparency block. Used by the texture unit definitions in the LOD block.

Transparency

• nTransparency AnimationBlocks at ofsTransparency, followed by data referenced in these records.

	Offset	Type	Name	Description
	0x10	ABlock	Alpha	A short for the alpha value. 0 - transparent, 0xFFFF - opaque.

Specifies global transparency values in addition to the values given in the Color block. I assume these are multiplied together eventually.

Textures

• Textures are defined globally in a list, additionally, a lookup table is given, referenced during rendering, to select textures.

Texture lookup table

• nTexLookup items starting at ofsTexLookup.

	Offset	Type	Name	Description
	0x00	uint16	TextureId	Array indices (0 to n-1).

Texture definitions

• First is a list of nTextures texture definition records, 16 bytes per record, starting at ofsTextures.

After it comes a string block with the texture filenames, which seems to have the same structure like the MOTX-Chunk in WMOs(see WMO), the "empty aligtments" are just the zeros were non "0 - hardcoded" type textures point too.

Offset	Type	Name	Description
0x000	uint32	Type	The type of the texture. See below.
0x002	uint16	Unknown	What do I know? Most likely just padding.
0x004	uint16	Flags	Textures have some flags. See below too.
0x008	uint32	lenFilename	Here is the length of the filename, if the type is not "0 - hardcoded" then it's just 1 and points to a zero
0x00C	uint32	ofsFilename	And the offset to the filename.

Texture Types

Texture type is 0 for regular textures, nonzero for skinned textures (filename not referenced in the M2 file!) For instance, in the NightElfFemale model, her eye glow is a type 0 texture and has a file name, the other 3 textures have types of 1, 2 and 6. The texture filenames for these come from client database files:

• DBFilesClient\CharSections.dbc
• DBFilesClient\CreatureDisplayInfo.dbc
• DBFilesClient\ItemDisplayInfo.dbc
• (possibly more)

	Value	Meaning
	0	Texture given in filename
	1	Body + clothes
	2	Cape
	6	Hair, beard
	8	Tauren fur
	11	Skin for creatures #1
	12	Skin for creatures #2
	13	Skin for creatures #3

Flags

	Value	Meaning
	1	Texture wrap X
	2	Texture wrap Y

Texture animation lookup table

• nTexAnimLookup items starting at ofsTexAnimLookup.

	Offset	Type	Name	Description
	0x00	uint16	AnimatedTextureId	Array indices (0 to n-1). -1 for a static texture.

Texture animations

• This block contains definitions for texture animations, for example, flowing water or lava in some models. The keyframe values are used in the texture transform matrix.

nTexAnims records of 0x54 bytes starting at ofsTexAnims, followed by data referenced in these records.

	Offset	Type	Description
	0x00	AnimationBlock (float, float, float)	Translation		0x1C	AnimationBlock (float, float, float ???)	Rotation?		0x38	AnimationBlock (float, float, float)	Scaling?

The three subrecords specify texture transforms. Translation seems to work, producing nice flowing lava and waterfalls.

Effects

Ribbon emitters

• nRibbonEmitters records of 0x9C bytes starting at ofsRibbonEmitters, followed by data referenced in these records.

The records have the following structure:

	Offset	Type	Name	Description
	0x00	uint32	Unknown	Always (as I have seen): -1.
	0x04	uint32	BoneID	A bone to attach to.
	0x08	float	Position[3]	And a position, relative to that bone.
	0x14	int32	nTextures	Number of referenced textures.
	0x18	int32	ofsTextures	Offset to the referenced textures.
	0x1C	int32	nUnkRef	Number of some referenced integers.
	0x20	int32	ofsUnkRef	Offset to the integers.
	0x24	ABlock	Color	A color in three floats.
	0x38	ABlock	Opacity	And an alpha value in a short, where: 0 - transparent, 0xFFFF - opaque.
	0x4C	ABlock	Above	The height above.
	0x60	ABlock	Below	The height below. Do not set these to the same!
	0x74	float	Resolution	This defines how smooth the ribbon is. A low value may produce a lot of edges.
	0x78	float	Length	The length aka Lifespan.
	0x7C	float	UnknownFloat	Usually 0
	0x80	short	UnknownShorts[2]	Maybe these are blending modes. Pairs of {1,1} for example.
	0x84	ABlock	UnknownABlock1	The value on these two are integers. First one is 0 all the time.
	0x98	ABlock	UnknownABlock2	And the second one is 1.

Some models that contain ribbon emitters and are viewable in the game world are: Wisps in BFD, Al'ar the Phoenix in Tempest Keep and any other phoenix models and the energy trails in the COT (not the actual instance, but the entrance cave in Tanaris Desert). Other models with ribbon emitters are spells and effects.

Parameters from the MDL format that are probably in here somewhere: emission rate, rows, cols ...?

Particle emitters

• nParticleEmitters records starting at ofsParticleEmitters, followed by data referenced in these records.

	Offset	Type	Name	Description
	0x000	uint32	Unknown	Always (as I have seen): -1.
	0x004	uint32	Flags	There are more flags now. Known: 0x1000 - do not billboard.
	0x008	float	Position[3]	The position. Relative to the following bone.
	0x014	uint16	Bone	The bone its attached to.
	0x016	uint16	Texture	And the texture that is used.
	0x018	uint32	nReferences1	The first number of integers referenced.
	0x01C	uint32	ofsReferences1	And the matching offset.
	0x020	uint32	nReferences2	The second number of integers referenced.
	0x024	uint32	ofsReferences2	And the matching offset again.
	0x028	uint8	BlendingType	A blending type for the particle. Maybe the same as at the renderflags.
	0x029	uint16	EmitterType	1 - Plane (rectangle), 2 - Sphere, 3 - Spline? (can't be bothered to find one)
	0x02B	uint16	ParticleType	Found below.
	0x02D	uint8	Padding
	0x02E	uint16	TextureTileRotation	Rotation for the texture tile. (Values: -1,0,1)
	0x030	uint16	TextureRows	How many different frames are on that texture? People should learn what rows and cols are.
	0x032	uint16	TextureCols	Its different everywhere. I just took it random.
	0x034	ABlock	EmissionSpeed	All of the following blocks should be floats.
	0x048	ABlock	SpeedVariation	Variation in the flying-speed. (range: 0 to 1)
	0x05C	ABlock	VerticalRange	Drifting away vertically. (range: 0 to pi)
	0x070	ABlock	HorizontalRange	They can do it horizontally too! (range: 0 to 2*pi)
	0x084	ABlock	Gravity	Fall down, apple!
	0x098	ABlock	Lifespan	Everyone has to die.
	0x0AC	uint32	unknownPadding	I don't know what these two values should do..
	0x0B0	ABlock	EmissionRate	Stread your particles, emitter.
	0x0C4	uint32	unknownPadding2	It could have been an array without them..
	0x0C8	ABlock	EmissionAreaLength	Well, you can do that in this area.
	0x0DC	ABlock	EmissionAreaWidth
	0x0F0	ABlock	Gravity2	A second gravity? Its strong.
	0x104	FBlock	ParticleColor	This one points to 3 floats defining red, green and blue.
	0x114	FBlock	ParticleOpacity?	Looks like opacity (short) --Igor; Most likely they all have 3 timestamps for {start, middle, end}.
	0x124	FBlock	ParticleSizes	It carries two floats per key. (x and y scale)
	0x134	int32	UnknownFields[10]	Always 0 as far as I see. Indices into the tiles on the texture?
	0x15C	float	UnknownFloats1[3]	They have something to do with the spread.
	0x168	float	Scale[3]	Wheey, its the scale!
	0x174	float	Slowdown	Slowpoke is slow.
	0x178	float	UnknownFloats2[2]	More unknown fields.
	0x180	float	Rotation	As a single value? Most likely only one axis then..
	0x184	float	UnknownFloats3[2]	More unknown fields.
	0x18C	float	Rot1[3]	Model Rotation 1
	0x198	float	Rot2[3]	Model Rotation 2
	0x1A4	float	Trans[3]	Model Translation
	0x1B0	float	UnknownFloats4[6]	Unknown, unknown, unknown, unknown, unknown...
	0x1C8	ABlock	EnabledIn	Maybe this has integers again. Has been in the earlier documentations. Enabled Anim Block.

About Slowdown: For a non-zero values, instead of travelling linearly the particles seem to slow down sooner. I can't work out the exact function but for a value of, say, 10, the particles pretty much stay in place. Not the same effect as gravity, though. Speed is multiplied by exp( -slowdown * t ).

About particle rotation: 0 for none, 1 to rotate the particle 360 degrees throughout its lifetime.

Rotation can be a float value greater or less one. Results look better if use it as a "phase shift": particle_rotate = randfloat(-sys->rotation * pi, sys->rotation * pi); --Igor

Particle types

	Value	Description
	0	"normal" particle
	1	large quad from the particle's origin to its position (used in Moonwell water effects)
	2	seems to be the same as 0 (found some in the Deeprun Tram blinky-lights-sign thing)

ParticleType is always 0 and, maybe, now (Flags & 0x40000) != 0 means "particles from origin to position". --Igor

The Fake-AnimationBlock

• Its pretty much like the real one but without the "header".

	Offset	Type	Name	Description
	0x000	uint32	nTimestamps	The number of timestamps.
	0x004	uint32	ofsTimestamps	And the offset to them.
	0x008	uint32	nKeys	The same number again. This time its the number of Keys / Values.
	0x00C	uint32	ofsKeys	And their offset.

Miscellaneous

Bounding volumes

• For some models a simplified bounding volume is given. This is probably used for collision detection?

Vertices

• nBoundingVertices vertices at ofsBoundingVertices.

	Offset	Type	Name	Description
	0x00	float	Coordinate[3]	This defines a vertex in x,y and z values.

Triangles

• nBoundingTriangles triples of uint16s at ofsBoundingTriangles.

	Offset	Type	Name	Description
	0x00	uint16	Index[3]	Specifies three vertices of the list above to build a triangle.

The number nBoundingTriangles once again contains the number of indices used, so divide by 3 to get the number of triangles.

Normals

• nBoundingNormals normals at ofsBoundingNormals.

	Offset	Type	Name	Description
	0x00	float	Vector[3]	This defines the normal for each vertex.

Each vertex also has a corresponding normal vector. Therefore, it should be true that nBoundingVertices = nBoundingNormals = nBoundingTriangles / 3.

Lights

• nLights records of 0x9A bytes starting at ofsLights, followed by data referenced in these records.

The records have the following structure:

	Offset	Type	Name	Description
	0x00	uint16	Type	Types are listed below.
	0x02	int16	Bone	If its attached to a bone, this is the bone. Else here is a nice -1.
	0x04	float	Position[3]	Where is this light?
	0x10	ABlock	AmbientColor	The ambient color. Three floats for RGB.
	0x24	ABlock	AmbientIntensity	A float for the intensity.
	0x38	ABlock	DiffuseColor	The diffuse color. Three floats for RGB.
	0x4C	ABlock	DiffuseIntensity	A float for the intensity again.
	0x60	ABlock	AttenuationStart	This defines, where the light starts to be.
	0x74	ABlock	AttenuationEnd	And where it stops.
	0x88	ABlock	Unknown	Its an integer and usually 1.

Two light types:

	Value	Description
	0	Directional
	1	Point light

Cameras

• nCameras records of 0x64 bytes starting at ofsCameras, followed by data referenced in these records.

	Offset	Type	Name	Description
	0x00	uint32	BoneID	-1 if attached to none? Its also documented as id elsewhere.
	0x04	float	FOV	No radians, no degrees. Multiply by 35 to get degrees.
	0x08	float	FarClipping	Where it stops to be drawn.
	0x0C	float	NearClipping	Far and near. Both of them.
	0x10	ABlock	TranslationPos	How the cameras position moves. Should be 3*floats.
	0x24	float	Position[3]	Where the camera is located.
	0x30	ABlock	TranslationTar	How the target moves. Should be 3*floats.
	0x44	float	Target[3]	Where the camera points to.
	0x50	ABlock	Scaling	The camera can have some roll-effect. Its 0 to 2*Pi.

These blocks are present in the "flyby" camera models which completely lack geometry and the main menu backdrop models which are supposed to have a fixed camera. Additionally, characters and monsters also have this block. The reason that non-mainmenu and non-geometry M2s have cameras was is you can see the unit's portrait.

Camera lookup table

• nCameraLookup 16-bit integers starting at ofsCameraLookup.

	Offset	Type	Name	Description
	0x00	uint16	CameraId	All cameras. Array indices (0 to n-1).

Attachments

Block 1

• nAttachments records of the following structure starting at ofsAttachments, followed by data referenced in these records.

	Offset	Type	Name	Description
	0x00	uint32	Id	Just an id. Is referenced in the lookup-block below too.
	0x04	uint32	Bone	Somewhere it has to be attached.
	0x08	float	Position[3]	Relative to that bone of course.
	0x14	ABlock	Data	Its an integer in the data. It has been 1 on all models I saw. Whatever.

This block specifies a bunch of locations on the body - hands, shoulders, head, back, knees etc. It is used to put items on a character. This seems very likely as this block also contains positions for sheathed weapons, a shield, etc.

Here's the list of position slots (by ID, or index in block P) for character models:

	ID	Description	ID	Description	ID	Description
	0	Left wrist / Mountpoint	12	Back	24	-
	1	Right palm	13	-	25	-
	2	Left palm	14	-	26	Right back sheath
	3	Right elbow	15	Bust	27	Left back sheath
	4	Left elbow	16	Bust	28	Middle back sheath
	5	Right shoulder	17	Face	29	Belly
	6	Left shoulder	18	Above character	30	Left back
	7	Right knee	19	Ground	31	Right back
	8	Left knee	20	Top of head	32	Left hip sheath
	9	-	21	Left palm	33	Right hip sheath
	10	-	22	Right palm	34	Bust
	11	Helmet	23	-	35	Right palm

For weapons, usually 5 of these points are present, which correspond to the 5 columns in ItemVisuals.dbc, which in turn has 5 models from ItemVisualEffects.dbc. This is for the weapon glowy effects and such. The effect ID is the last column in ItemDisplayInfo.dbc. They take the ids 0 to 4. Mounts take the id 0 for their rider.

Attachment Lookup

• nAttachLookup 16-bit integers starting at ofsAttachLookup.

	Offset	Type	Name	Description
	0x00	uint16	Attachment	From 0 to nAttachments-1

Block 2

• nAttachments_2 records of 0x14 bytes starting at ofsAttachments_2, followed by "data" referenced in these records.

This might be definitions for weapon attachment slots or something like that... Mostly present on characters, creatures and items.

	Offset	Type	Name	Description
	0x00	char	Identifier[4]	Some kind of ID, starts with '$'. Some identifiers below.
	0x04	uint32	Id	Just an id. Is referenced in the lookup-block below too.
	0x08	uint32	Bone	Somewhere it has to be attached.
	0x0C	float	Position[3]	Relative to that bone of course.
	0x08	uint16	InterpolationType	This is some fake-AnimationBlock.
	0x0A	uint16	GlobalSequence	Built up like a real one but without values. What the fuck?
	0x0C	uint32	nTimestamps	See the documentation on AnimationBlocks at this topic.
	0x10	uint32	ofsTimestamps	Will most likely be the same shit again as in the real ones.

Each record specifies a transformation matrix for attaching another model to a certain point. By translating to the attachment position and then applying the transform matrix of the parent bone, the other model at its default origin will snap right into place. This is how weapons are affixed to the hands, helmets and shoulder armor attached, and spell effects are also positioned this way.

Some position identifiers:

	ID	Description
	$TRD	Crotch
	$CCH	Bust
	$BTH	In front of head
	$CHD	Head
	$SHL, $SHR	Left/right shoulder
	$CSL, $CSR	Left/right hand
	$BWP, $BWR	Right hand (for weapons maybe?)

The rest are either copies of the crotch position, or down on the floor. I suppose these are used to position spell effects (like a levelup flash or something) and damage effects.