string = text .size (0..64)
policy_id = string / bytes ; hex string for CIP-25 version 1, bytes version 2
asset_name = string / bytes ; utf-8 for CIP-25 version 1, bytes for version 2

artist_details =
  {
    name: string,
    ? isni : string,
    ? links: { * string => string },
  }

author_details =
  {
    name: string,
    ? ipi: string,
    ? share: string,
  }

contributing_artist_details =
  {
    name: string,
    ? ipn: string,
    ? ipi: string,
    ? role: [* string],
    ? links: { * string => string }
  }

common_music_details = (
  ? artists : [+ artist_details],
  ? genres: [1*3 string],
  ? copyright: { master: string, composition: string },
  ? contributing_artists : [* contributing_artist_details]
)

release_details = 
  {
    release_type: "Single" / "Multiple" / "Album/EP",
    release_title : string,
    ? distributor: string,
    ? visual_artist: string,
    ? release_date: string,
    ? publication_date: string,
    ? catalog_number: string,
    ? series: string,
    ? collection: string,
  } // Extend with common_music_details when release_type is "Album/EP"
  (release_details.release_type == "Album/EP" => common_music_details)

song_details = 
  {
    song_title: string / [* string],
    song_duration: string .regexp "^P(?!$)(T(?=\d)(\d+H)?(\d+M)?(\d+S)?)$",
    track_number: uint,
    
    ? featured_artists : [* artist_details],
    ? authors: [* author_details],
    ? mood: string,
    ? set: string,
    ? lyrics: string,
    ? special_thanks: [* string],
    ? bitrate: string,
    ? bpm: string,
    ? mix_engineer: string,
    ? mastering_engineer: string,
    ? producer: string,
    ? co_producer: string,
    ? recording_engineer: string,
    ? explicit: bool,
    ? isrc: string,
    ? iswc: string,
    ? metadata_language: string,
    ? country_of_origin: string,
    ? language: string,
    ? derived_from: string,
    ? ai_generated: bool,
  } // Include common_music_details only when release_type is not "Album/EP"
  (release_details.release_type != "Album/EP" => common_music_details)

files_details = 
  {
    name : string,
    mediaType : string,
    src : string,
    song : song_details,
  }  

metadata_details = 
  {
    name : string,
    image : string,
    music_metadata_version: 3,
    release: release_details,
    files : [+ files_details],
    
    ? version: 1 / 2,
    ? mediaType : string,
    ? description : string / [* string],
  }

label_metadata = { * policy_id => { * asset_name => metadata_details } }
metadata = { 721 : label_metadata }