ISO Data File Format Layout - LordNed/WindEditor GitHub Wiki

This document outlines what kind of data is stored where on the game's disk. This should be considered a relatively high-level overview.

/&&SystemData/ - Stores the game's executable and files associated with that.
/Audiores/ - Stores audio data for music, cutscenes, etc.
/maps/ - Symbol Dumps for all .rels and .elf in game. Symbols are scrambled.
/rels/ - First set of .rel (contains actors, objects, etc.)
/res/ - Game Content
/thpdemo/ - Contains video for end game cutscene and idle loop played during title screen.
rels.arc - Contains second set of .rel files for the game, sorted into two sub folders - amem and memm.
COPYDATE - Contains a single date inside of it (presumably build time for disk image)
framework.str - Contains list of .plf file locations
opening.bnr - Banner containing game logo shown in Dolphin and in GC OS menu.

/Banks/ - Sound Effects, Instrument Samples
/Stream/ - Streams used for Cutscenes. Presumably streamed in on the fly as needed.
/Seqs/ - Sequenced music used for normal music. (MIDI like)

/ActorDat/ - Contains the enemy drop file which specifies what actors drop what items.
/CardIcon/ - Image used on the memory card (presumed)
/Fmap/ - Sea Chart Data
/FmapDat/ - Sea Chart
/Gba/ - Resources required for Tingle Tuner Connectivity (presumed)
/ItemTable/ - Contains the item drop table which specifies what items (plants, flowers) drop what items.
/Menu/ - Contains the debug menu used to load specific maps without playing through game.
/Msg/ - Various data/resources lots of UI layout data.
/Object/ - Archives for all of the objects in the game.
/Particle/ - Particle packs for various scenes in the game. Not specific particles.
/Photo/ - Legendary Photos with .dds extension. Don't actually appear to be DDS files (or maybe they're big-endian?)
/placename/ - Images for the place-name cards shown when you first get to a location
/Stage/ - Holds all of the map data for all of the maps in the game, both overworld and interior.