> ## Documentation Index > Fetch the complete documentation index at: https://musicready.org/llms.txt > Use this file to discover all available pages before exploring further. # MRS-S Measures & Events > Measure structure and event syntax in MRS-S. See: [`/MRS-Specification-RFC#4-mrs-s-the-canonical-storage-format`](/MRS-Specification-RFC#4-mrs-s-the-canonical-storage-format) ## Measures Section ```clojure theme={null} (measures (measure :id #uuid "018c3f40-0001-7890-abcd-ef1234567890" :number 1 :beat-start 0 :time 4/4 :key C :mode minor :tempo 120 (flute-1 (v1 (: 0 C5.q :id #uuid "018c3f2a-0001-...") (: 1 D5.q :id #uuid "018c3f2a-0002-...") (: 2 E5.h :id #uuid "018c3f2a-0003-..."))) (clarinet-bb (v1 (: 0 r.w :id #uuid "018c3f2a-0010-..."))))) ``` ### Measure Attributes | Attribute | Required | Type | Description | | ---------------- | -------- | ----------- | ---------------------------------------------- | | `:id` | YES | UUIDv7 | Stable identifier | | `:number` | YES | integer | Display number (can have gaps) | | `:beat-start` | YES | rational | Absolute beat position (orchestrator-computed) | | `:time` | NO | fraction | Time signature (inherits if omitted) | | `:key` | NO | pitch-class | Key signature (inherits if omitted) | | `:mode` | NO | keyword | Mode (inherits if omitted) | | `:tempo` | NO | integer | Tempo in BPM (inherits if omitted) | | `:tempo-text` | NO | string | Tempo marking text | | `:rehearsal` | NO | string | Rehearsal mark | | `:barline-left` | NO | keyword | Left barline type | | `:barline-right` | NO | keyword | Right barline type | ### Attribute Inheritance | Attribute | Inherits? | | ----------------------- | ------------------- | | `:time` | Yes, until changed | | `:key`, `:mode` | Yes, until changed | | `:tempo`, `:tempo-text` | Yes, until changed | | `:rehearsal` | No (single-measure) | | `:barline-*` | No (per-measure) | ### Barline Types ``` none single double final repeat-start repeat-end repeat-both ``` ## Instrument Content Within a measure, content is organized by instrument: ```clojure theme={null} (measure :id #uuid "..." :number 1 (flute-1 (v1 ...)) (clarinet-bb (v1 ...) (v2 ...)) (piano (:rh (v1 ...)) (:lh (v1 ...)))) ``` ### Voice Naming | Instrument Type | Voice Names | | --------------- | --------------------------------------- | | Single-staff | `v1` through `v4` | | Keyboard | `:rh`/`:lh` containing `v1`, `v2`, etc. | ## Event Syntax ```clojure theme={null} (: :id *) ``` | Component | Description | | -------------- | -------------------------------------------------- | | `:` | Event marker | | `` | Beat position within measure (0-indexed, rational) | | `` | Pitch, chord, or rest | | `:id` | Stable UUIDv7 identifier (REQUIRED) | | `` | Optional `:keyword value` pairs | ### Examples ```clojure theme={null} (: 0 C5.q :id #uuid "...") ; C5 quarter on beat 0 (: 1 Eb4.e :id #uuid "..." :dyn f) ; Eb4 eighth on beat 1, forte (: 2+1/2 [C4 E4 G4].q :id #uuid "...") ; Chord on beat 2.5 (: 3 r.q :id #uuid "...") ; Quarter rest on beat 3 ``` ### Beat Position Beat positions are **exact rationals** relative to measure start (0-indexed): ``` 4/4 time: 0 = Beat 1 (downbeat) 1 = Beat 2 2 = Beat 3 3 = Beat 4 0+1/2 = "And" of beat 1 1+3/4 = Fourth sixteenth of beat 2 6/8 time (compound): 0 = Downbeat 1 = Dotted quarter 2 0+1/3 = First eighth subdivision ``` **Canonical form**: Use integers for whole beats, mixed numbers for fractions: * `0`, `1`, `2` (integers) * `2+1/2` (two and a half) * `0+1/3` (one third) Decimal literals (`2.5`) are NOT permitted. ## Pitch Expression ### Single Note ```clojure theme={null} C4.q ; C4 quarter note Eb5.h ; E-flat 5 half note F#3.e ; F-sharp 3 eighth note Bbb4.w ; B double-flat 4 whole note Cx4.s ; C double-sharp 4 sixteenth note ``` ### Chord ```clojure theme={null} [C4 E4 G4].q ; C major triad, quarter [D3 F#3 A3 C4].h ; D7 chord, half note ``` ### Rest ```clojure theme={null} r.q ; Quarter rest r.h ; Half rest r.w ; Whole rest ``` ## Duration Codes | Code | Name | Beats | | ---- | ------------- | ----- | | `w` | Whole | 4 | | `h` | Half | 2 | | `q` | Quarter | 1 | | `e` | Eighth | 1/2 | | `s` | Sixteenth | 1/4 | | `t` | Thirty-second | 1/8 | | `x` | Sixty-fourth | 1/16 | ### Dotted Durations | Code | Name | Beats | | ----- | --------------------- | ----- | | `q.` | Dotted quarter | 3/2 | | `h.` | Dotted half | 3 | | `q..` | Double-dotted quarter | 7/4 | ## Event Properties ```clojure theme={null} (: 0 G4.q :id #uuid "018c3f2a-..." :dyn ff :art staccato :orn trill :tech pizz :lyrics [{:text "Hal-" :syllabic begin}] :grace true :cue true :cue-source violin-1) ``` | Property | Type | Description | | ------------- | ------------- | ----------------- | | `:dyn` | keyword | Dynamic marking | | `:art` | keyword | Articulation | | `:orn` | keyword | Ornament | | `:tech` | keyword | Playing technique | | `:lyrics` | list | Lyric syllables | | `:grace` | boolean | Grace note | | `:cue` | boolean | Cue note | | `:cue-source` | instrument-id | Source for cue | ### Dynamics ``` pppp ppp pp p mp mf f ff fff ffff sfz sfp sffz fz rf rfz fp sf ``` ### Articulations ``` staccato staccatissimo tenuto accent marcato portato fermata breath caesura ``` ### Ornaments ``` trill mordent mordent-inverted turn turn-inverted tremolo arpeggio glissando ``` ### Techniques (Strings) ``` arco pizz pizz-snap pont tasto normale harm harm-natural harm-artificial spicc detache martele ``` ### Techniques (Winds) ``` tongue double-tongue triple-tongue flutter cuivre stopped open mute-straight ``` ## Tuplets ```clojure theme={null} (tuplet 3:2 q (: 0 C4.e :id #uuid "...") (: 0+1/3 D4.e :id #uuid "...") (: 0+2/3 E4.e :id #uuid "...")) ``` Triplet: 3 notes in the space of 2 quarters. ## Grace Notes ```clojure theme={null} (grace :type acciaccatura (: 0 D5.s :id #uuid "...")) (: 0 C5.q :id #uuid "...") ; Main note ``` Grace types: `acciaccatura`, `appoggiatura`