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Type	Length	Description
Float	4
Int32	4	Signed
UInt32	4	Unsigned
UInt64	8	Unsigned
Bool	4	True if 1, else false
Int16	2	Signed
UInt16	2	Unsigned
ChunkName	4	RIFF-style chunk identifier
UTF8String		Null-terminated

Complex types

String

StringAddress : Int32 //The value is an UTF8String

List<T>

AddressCount : Int32
Addresses : Int32[AddressCount]
T[Addresses.Length]

Chunk

Name : ChunkName
Length : Int32

ListChunk<T> : Chunk

List<T>

RefDefEListChunk : Chunk Only valid for bytecode version 0xE (see FUNC/VARI for 0xF)

RefDefEList : RefDefE[] //Read until end; logic explained in decompilation process
- Name : String
- Occurrences : Int32
- FirstAddress : Int32

Form : Chunk

Gen8 : Chunk //Metadata
- Debug : Byte
- unknown : Int24
- Filename : String
- Config : String
- LastObj : UInt32 // possibly the last offset of all objects, but this is untested
- LastTile : UInt32 // idem
- GameID : UInt32
- unknown : UInt32[4]
- Name : String
- Major : Int32
- Minor : Int32
- Release : Int32
- Build : Int32
- DefaultWindowWidth : Int32
- DefaultWindowHeight : Int32
- Info : InfoFlags
- LicenseMD5 : Byte[0x10]
- LicenseCRC32 : UInt32
- Timestamp : UInt64 // UNIX time
- DisplayName : String
- ActiveTargets : GameTargets // probably flags indicating for which platforms the file is built, but no flag values are known at this point
- unknown : UInt32[4]
- SteamAppID : UInt32
- NumberCount : UInt32
- Numbers : UInt32[NumberCount]
Optn : Chunk
- unknown : UInt32[2]
- Info : InfoFlags // duplicate from GEN8
- unknown : UInt32[0xC]
- ConstantMap : List<Constant>
  - Name : String
  - Value : String
Extn : Chunk //Empty // NOTE: a rough structure is known, but too vague to include here. Read the Altar.NET src
Sond : Chunk //Sound data
- Name : String
- Flags : SoundEntryFlags
- Type : String
- File : String
- unknown : UInt32
- Volume : Float
- Pitch : Float
- GroupID : Int32 // to AGRP
- AudioID : Int32 // actual audio data, -1 when not embedded
Agrp : ListChunk<AudioGroup>
- Name : String
Sprt : ListChunk<Sprite>
- Name : String
- Width : Int32
- Height : Int32
- MarginLeft : Int32
- MarginRight : Int32
- MarginBottom : Int32
- MarginTop : Int32
- unknown : UInt32[3] // maybe something with collision masks
- BBoxMode : UInt32
- SepMasks : UInt32
- OriginX : UInt32
- OriginY : UInt32
- TextureCount : Int32
- TextureAddresses : Int32[TextureCount] // to TPAG
- Unknown : Byte[] //Until next object
Bgnd : ListChunk<Background>
- Name : String
- unknown : UInt32[3]
- TextureAddress : Int32 // to TPAG
Path : ListChunk<Path> //Paths
- Name : String
- IsSmooth : Bool
- IsClosed : Bool
- Precision : UInt32
- Points : List<UInt32>
  - X : Float
  - Y : Float
  - Speed : Float
Scpt : ListChunk<ScriptDefinition>
- Name : String
- Id : UInt32 // to CODE
Shdr : Chunk //Empty
Font : Chunk //Fonts
- CodeName : String
- SystemName : String
- EmSize : UInt32
- Bold : Bool
- Italic : Bool
- RangeStart : UInt16 // ignore this, use the character list instead
- Charset : Byte
- AntiAliasing : Byte
- RangeEnd : UInt32
- TPagId : UInt32 // TPAG containing the glyphs
- ScaleX : Float
- ScaleY : Float
- Glyphs : List<Glyph>
  - Character : UInt16 // 16-bit codepoint
  - RelativeX : UInt16
  - RelativeY : UInt16
  - unknown : Byte[6]
Tmln : Chunk //Empty
Objt : ListChunk<GameObjectDefinition>
- Name : String
- SpriteIndex : Int32
- Visible : Bool
- Solid : Bool
- Depth : Int32
- Persistent : Bool
- ParentId : Int32 // -1 if none
- TextureMaskId : Int32 // -1 if none
- UsesPhysics : Bool
- IsSensor : Bool
- CollisionShape : CollisionShape
- Physics : ObjectPhysics
  - Density : Float
  - Restitution : Float
  - Group : Float
  - LinearDamping : Float
  - AngularDamping : Float
  - unknown : Float
  - Friction : Float
  - unknown : Float
  - Kinematic : Float
  // NOTE: sometimes, more floats are here as well, the exact conditions are unknown. See the Altar.NET source.
- ShapePointCount : UInt32
- ShapePointOffsets : UInt32 // read the Altar.NET source
Room : ListChunk<Room>
- Name : String
- Caption : String
- Width : UInt32
- Height : UInt32
- Speed : UInt32
- Persistent : Bool
- Argb : UInt32
- DrawBGColor : Bool
- unknown : UInt32
- Flags : RoomEntryFlags
- BgOffset : UInt32 // offsets to the List<T> later on
- ViewOffset : UInt32
- ObjOffset : UInt32
- TileOffset : UInt32
- World : UInt32
- Top : UInt32
- Left : UInt32
- Right : UInt32
- Bottom : UInt32
- GravityX : Float
- GravityY : Float
- MetresPerPixel : Float
- Backgrounds : List<Background>
  - Enabled : Bool
  - Foreground : Bool
  - BgDefIndex : UInt32
  - X : UInt32
  - Y : UInt32
  - TileX : Bool
  - TileY : Bool
  - SpeedX : UInt32
  - SpeedX : UInt32
  - ObjectId : Int32
- Views : List<View>
  - Enabled : Bool
  - ViewX : Int32
  - ViewY : Int32
  - ViewWidth : Int32
  - ViewHeight : Int32
  - PortX : Int32
  - PortY : Int32
  - PortWidth : Int32
  - PortHeight : Int32
  - BorderX : UInt32
  - BorderY : UInt32
  - SpeedX : UInt32
  - SpeedY : UInt32
  - ObjectId : Int32
- GameObjects : List<GameObject>
  - X : Int32
  - Y : Int32
  - BgDefIndex : Int32
  - InstanceID : Int32
  - CreationCodeID : Int32 // to CODE (-1 for none) -> gml_RoomCC_<name>_<CreationCodeID>
  - ScaleX : Float
  - ScaleY : Float
  - ARGBTint : UInt32
  - Rotation : Float
- Tiles : List<Tile>
  - X : Int32
  - Y : Int32
  - BgDefIndex : Int32
  - SourceX : Int32
  - SourceY : Int32
  - Width : UInt32
  - Height : UInt32
  - TileDepth : Int32
  - InstanceID : Int32
  - ScaleX : Float
  - ScaleY : Float
  - ARGBTint : UInt32
Dafl : Chunk //Empty
Tpag : ListChunk<Texture>
- X : UInt16
- Y : UInt16
- Width : UInt16
- Height : UInt16
- RenderX : UInt16
- RenderY : UInt16
- BoundingX : UInt16
- BoundingY : UInt16
- BoundingWidth : UInt16
- BoundingHeight : UInt16
- SpritesheetId : UInt16
Code : ListChunk<CodeE> // bytecode version 0xE
- Name : String
- Length : UInt32
- Code : Byte[Length] // or until next object
Code : ListChunk<CodeF> // bytecode version 0xF
- Name : String
- Length : UInt32
- unknown : UInt32
- BytecodeAddress : Int32 // offset to the actual bytecode, relative to this value
- unknown : UInt32
Vari : RefDefEListChunk // if bytecode version == 0xE
Vari : ListChunk&lit;VariableDefinition> // if bytecode version == 0xF
- Name : String
- unknown : UInt32[2]
- Occurrences : UInt32
- FirstAddress : UInt32
Func : RefDefEListChunk // for both bytecode versions, it seems
// For detailed information on RefDef parsing, read the Altar.NET source
Strg : ListChunk<StringDefinition>
- Length : UInt32
- Value : UTF8String
Txtr : ListChunk<Spritesheet>
- unknown : UInt32
- PngAddress : UInt32
Audo : ListChunk<Audio>
- Length : UInt32
- WavBlob : Byte[Length] // or was it Length + 4?

Primitive types

Enum types

Complex types