Data Model

Score
├── meta: Metadata
├── players: List<Player>
├── instruments: List<Instrument>
├── measures: List<Measure> | movements: List<Movement>
├── spans: List<Span>
├── overlays: List<Overlay>?
├── structural-index: StructuralIndex?
└── alternatives: List<Alternative>?

Player
├── id: Identifier
├── name: String
├── instruments: List<InstrumentId>
└── default: InstrumentId

(player woodwind-2
  :name "Flute 2 / Piccolo"
  :instruments [flute-2 piccolo]
  :default flute-2)

Instrument
├── id: Identifier
├── name: String
├── abbr: String
├── family: InstrumentFamily
├── staves: List<Clef>
├── transposition: Interval | none
├── range: [Pitch, Pitch]?
├── kit: List<KitItem>?  ; percussion only
└── staff-connect: ConnectType?

(instrument clarinet-bb
  :name "Clarinet in Bb"
  :abbr "Cl."
  :family woodwinds
  :staves [treble]
  :transposition (down M2)
  :range [E3 C7])

woodwinds brass strings percussion keyboards voices choir other

Measure
├── id: UUIDv7              ; Stable identity
├── number: Integer         ; Display number
├── beat-start: Rational    ; Orchestrator-computed
├── time: TimeSignature?    ; Inherits if omitted
├── key: PitchClass?        ; Inherits if omitted
├── mode: Mode?             ; Inherits if omitted
├── tempo: Integer?         ; Inherits if omitted
├── tempo-text: String?
├── rehearsal: String?
├── barline-left: BarlineType?
├── barline-right: BarlineType?
├── directions: List<Direction>
└── content: Map<InstrumentId, InstrumentContent>

Event
├── beat: Rational          ; Position within measure (0-indexed)
├── pitch: PitchExpr        ; Pitch, chord, or rest
├── id: UUIDv7              ; Stable identity
├── dyn: Dynamic?
├── art: Articulation?
├── orn: Ornament?
├── tech: Technique?
├── lyrics: List<LyricSyllable>?
├── grace: Boolean?
├── cue: Boolean?
├── cue-source: InstrumentId?
└── ...other properties

event.:at = measure.:beat-start + event.beat

Span
├── id: UUIDv7
├── type: SpanType
├── from: UUIDv7?           ; Start event (for from/to spans)
├── to: UUIDv7?             ; End event (for from/to spans)
├── events: List<UUIDv7>?   ; Event list (for beams)
├── boundary-entry: Boolean?
├── boundary-exit: Boolean?
└── ...type-specific attributes

Canonical forms:
  0, 1, 2, ...       ; Integers
  2+1/2              ; Two and a half
  0+1/3              ; One third
  3+3/4              ; Three and three quarters

NOT permitted:
  2.5                ; Decimal
  0.333              ; Decimal

(v1
  (layer 1
    (: 0 C4.q :id #uuid "...") (: 1 D4.q :id #uuid "..."))
  (layer 2
    (: 0 E4.q :id #uuid "...") (: 1 F4.q :id #uuid "...")))

(harmony-plan
  (region :measures #uuid "..." #uuid "..."
    (chord :beat 0 :symbol Cm :function i)
    (chord :beat 2 :symbol Fm :function iv)))