Maps and archetypes

A YMAP places entities; a YTYP defines the archetypes those entities name. Both are META resources, so their stored descriptions identify fields rather than requiring a single hard-coded record layout for every file. Proven

Every one of the install’s 19,941 YMAP and 2,869 YTYP copies decodes through its full META tree, with no refused files or unreached data-block bytes. This covers the stored map/archetype fields and enum descriptions below, while runtime orientation and activation rules retain their separate observation scope. Proven · all YMAP and YTYP entries

Map data

CMapData holds its name hash, parent-map hash, flags, content flags, streaming extents, entity extents, entity array and physics-dictionary references. A zero parent hash means no parent map. Proven

Field group	Stored content	Confidence
streamingExtentsMin/Max	Streaming bounding box	Proven
entitiesExtentsMin/Max	Entity bounding box, separate from the streaming box	Proven
entities	CEntityDef or CMloInstanceDef references	Proven
physicsDictionaries	Collision dictionary hashes	Proven
Other arrays	Occluders, grass batches, lights, car generators and extensions	Proven

A CEntityDef names an archetype and carries flags, GUID, position, quaternion, XY and Z scale, parent index, LOD distances, LOD level, child count, priority, ambient-occlusion values and tint value. The two scale fields represent (scaleXY, scaleXY, scaleZ). Proven

The world coordinate frame is east, north, up, in metres. Ordinary entity orientation uses the conjugate of the stored (x,y,z,w) quaternion; an interior instance uses its stored quaternion directly. Observed The interior rule has a check against the game’s own data: in the interior proxies of gta5_cache_y.dat the stored quaternion fits 163 rotated interiors and its conjugate fits none. Sourced · ragekit The ordinary-entity convention comes from CodeWalker, and the other readers copy it rather than confirm it. Sourced · CodeWalker

Archetypes

CMapTypes contains archetypes of three kinds. Proven

Structure	Additional role	Confidence
CBaseArchetypeDef	Base asset definition	Proven
CTimeArchetypeDef	Adds timeFlags, selecting hours	Proven
CMloArchetypeDef	Interior with local entities, rooms, portals and entity sets	Proven

The base definition holds name, LOD distance, flags, special attribute, bounding box and sphere, HD texture distance, texture/clip/drawable/physics dictionary hashes, asset type and asset-name hash. Proven

Asset type	Payload	Confidence
0	Uninitialized	Proven
1	Fragment (yft)	Proven
2	Drawable (ydr)	Proven
3	Drawable-dictionary (ydd) entry	Proven
4	Asset-less	Proven

An interior’s local placements inherit the placed instance’s rotation and position. Script-controlled entity sets are separate from that interior’s base entity list. Observed

Streaming and scripts

Map flag bit 0 marks script-managed maps, commonly requested as IPLs. A child map whose parent chain reaches a script-managed map shares that activation dependency. The stored bit does not establish whether startup scripts activate that map in a particular save. Observed

Story and Online select different active files through mount changes. Keeping both sets simultaneously without their state conditions can duplicate mutually exclusive world content. Observed

Content outside the maps

Some visible world objects are in no map file. The Del Perro pier Ferris wheel, prop_ld_ferris_wheel, is spawned by scripts (am_ferriswheel.ysc, bigwheel.ysc, armenian1.ysc, finalec2.ysc) with its hub at (−1663.97, −1126.70, 30.70) and 16 prop_ferris_car_01 cars at radius 15.5 m, every 22.5°. Observed

Street litter such as bottles, cans and paper is absent from the map placements. Observed It is spawned as procedural objects, which the procedural ID of collision materials selects. Inferred

What is the complete startup IPL and interior-entity-set state?

Map and archetype files describe available content; they do not establish all script requests for a save or mission. Unknown