Levels and layer PAKs

A level is not one file. The ten base PAKs in levels (CHARLIE.PAK to PAPA.PAK, named for the NATO letters of the hub) hold the geometry that every map of the level shares; layer PAKs in levels/layers hold the rest: lighting, navigation, the gameplay sessions, the difficulty settings. A map is a base plus the layers its load script names. The disc has 10 base PAKs and 209 layer PAKs. Proven · all 336 PAKs

Layer names

A layer PAK is named by eight hex digits DS0000ZZ (88000004.pak is casual, session type 8 (tutorial), map 04; a200000f.pak is hardcore, session type 2, map 0F). Proven · all 209 layer PAKs

Digit	Meaning	Values
D	difficulty	0 none, 8 casual, 9 confident, A hardcore
S	session type: the id of session_types (MAIN.DB)	0 challenge, 1 trick, 2 speed, 3 free skate, 4 scoring spots, 5 showcase, 6 ESSKATE, 7 manual, 8 tutorial, 9 survival, A big air, B grind (10 and 11 in the table)
ZZ	map id	below

186 of the layer PAKs have a nonzero difficulty digit and 23 have none. The 000000ZZ PAKs are the always-loaded set of a map (lighting, standard session, navigation splines, level-specific data); the PAKs with a difficulty digit of 8, 9 or A hold the session layer of that session type at that difficulty. Observed

Map id	Map
04	Charlie (training, challenges)
05, 06, 07	Delta, Echo, Foxtrot
0A, 0B	India, Juliet
0C, 0D, 0E	Mike, lower (Kilo), combo (Lima) and upper (Mike)
0F, 10, 11	November, Oscar, Papa
16, 17, 21	Charlie big air 2, 3 and 1
18, 19, 1A	Charlie manual 1 to 3 (pro challenges)
1E, 1F, 20	Charlie grind 1 to 3
22, 23	Delta half-pipe 1, Delta big air

The maps of one level share its base PAK; CHARLIE has ten map ids. Observed

What a layer holds

Counted over the SCPs of the disc (SCP tables). Observed

Layer	Content
lighting_*	one node and light or probe sections only; no placements
navsplinedata	navigation guide splines and NavJunction chunks; no placements
standardsession	two nodes and nothing else
base and the challenge, trick, speed, freeskate, scoringspot sessions	geometry placements, spot chunks and AI path splines
casual, confident, hardcore difficulty	spot chunks (SafeRespawn, Attractor, Spot, triggers); for casual also a few placements (ribbon and guidance meshes)
saferespawndata	SafeRespawn and Spot chunk pairs only; exists in the 9 and A PAKs, not in casual

The geometry of a map is therefore the base PAK plus its layers: CHARLIE’s base has 85 placements, its trainingsession1 layer 2,558, its challengesession 227, and its big-air, grind and pro-challenge maps 4,000 to 5,000 each. Proven · all 547 SCPs The casual difficulty layer’s constants name the ribbon textures casual_path/ribbon_casual and casualplus, which is how the guide ribbons are identified. Inferred

Load order

The level script named by the levels row (script\level_load_<name>.lua, compiled Lua 5.1 in SCRIPTS.SDAT) lists the layers to load as LoadData('<layer>\<layer>') constants, read from the script’s constant table without running it. The common order is lighting_default (then LoadLighting), standardsession, navsplinedata, then the level-specific layers (TrainingSession1, challengesession, AAP_*, secretspeeddata, BigAir2, …), and the actor scripts (Actors/<City>_Ambient|Imposters|AI_Rail.lua) follow. Observed The navigation script (level_load_navigation.lua, LoadNavigationData) loads the difficulty layer. Observed Each such LoadData constant is one quartet in a layer PAK, listed by the PAK’s entries. Observed The base PAK is the PATH of the level row, which no Lua constant names; that is the reason for the base being taken from the row. Inferred

What a session opens

A trace of the files the running game opens (in an emulator, from the menu to the level) shows which layer PAKs a session loads besides its base. Observed · five sessions on three levels

Session	PAKs opened	Confidence
CHARLIE training lesson	00000004, 88000004	Observed
INDIA (New Orleans) Quick Play, Trick	india.pak, 0000000a, 8100000a	Observed
INDIA, the Point Rush that followed	8200000a	Observed
INDIA Free Ride	india.pak, 0000000a, 8300000a	Observed
MIKE Free Ride	mike.pak, 0000000e, 8300000e	Observed

Each session opens the map’s always-loaded 000000ZZ PAK and one PAK whose session digit is its own session type (1 trick, 2 speed, 3 free skate, 8 tutorial), all at the casual difficulty digit 8 in these runs. Observed For INDIA and MIKE Free Ride these are exactly the PAKs found by taking the level row’s first session of type FREE in MAIN.DB and naming the layer by the rule above. Observed

Opened is not drawn

A layer PAK holds several quartets, and the game does not draw all of a PAK it opens. In the CHARLIE training lesson the trainingsession1 and trainingsession2 quartets are drawn, while the meshes of the challengesession quartet in 00000004 (mats, magenta arrows, a green board and a white cone) and of the casualdifficulty quartet in 88000004 (yellow boards) are not, although both PAKs are open. Observed · a frame of the running game against a render of every placement of the opened quartets The level script asks for challengesession with LoadData whatever the session, and during training can also ask for casualdifficulty and TrainingSession2, so the script’s requests do not decide what is drawn either. Observed · static reading of the scripts The loader passes the session and navigation bits of what it loads into separate collections; which code turns a collection’s meshes on is not established. Observed · static reading of the executable

What decides which quartets of an opened PAK are drawn?

Neither the PAKs opened nor the LoadData requests give the set that is drawn. The consumers of the loader’s session and navigation collections, or a trace of them while a session runs, would.

Missing levels

Rows of the levels table with no PAK on the disc: Bravo, Golf and Hotel (placeholders), EchoProC and IndiaProC (pro-challenge sessions), HorseSession1 to 3 and halfpipesession2. Their scripts exist and their content does not. Observed

Which scripts join a map id to its layers?

The mapping from a database row to its map id is made by the load scripts. The names of layers come from their constants, but the join itself was not run, so no reader chooses a map for a row; it is left to the program that loads the level.