3.2.150 stem-interface (LilyPond Internals Reference)

#### 3.2.150 `stem-interface`

The stem represents the graphical stem. In addition, it internally connects note heads, beams, and tremolos. Rests and whole notes have invisible stems.

The following properties may be set in the `details` list.

`beamed-extreme-minimum-free-lengths`

  List of extreme minimum free stem lengths (chord to beams) given beam multiplicity.

`beamed-lengths`

  List of stem lengths given beam multiplicity.

`beamed-minimum-free-lengths`

  List of normal minimum free stem lengths (chord to beams) given beam multiplicity.

`lengths`

  Default stem lengths. The list gives a length for each flag count. If a list entry is a pair, it gives the stem length for the specific up and down stem, respectively.

`stem-shorten`

  How much a stem in a forced direction should be shortened. The list gives an amount depending on the number of flags and beams.

#### User-settable properties:

> `avoid-note-head` (boolean)

>   If set, the stem of a chord does not pass through all note heads, but starts at the last note head.

> `beaming` (pair)

>   Pair of number lists. Each number list specifies which beams to make. `0` is the central beam, `1` is the next beam toward the note, etc. This information is used to determine how to connect the beaming patterns from stem to stem inside a beam.

> `beamlet-default-length` (pair)

>   A pair of numbers. The first number specifies the default length of a beamlet that sticks out of the left hand side of this stem; the second number specifies the default length of the beamlet to the right. The actual length of a beamlet is determined by taking either the default length or the length specified by `beamlet-max-length-proportion`, whichever is smaller.

> `beamlet-max-length-proportion` (pair)

>   The maximum length of a beamlet, as a proportion of the distance between two adjacent stems.

> `default-direction` (direction)

>   Direction determined by note head positions.

> `details` (alist, with symbols as keys)

>   An alist of parameters for detailed grob behavior. See All layout objects for more information on the available parameters and their default values of a particular grob’s `details` property. See Graphical Object Interfaces for documentation of the available parameters. Supporting interfaces can be found at the bottom of a grob’s description section.

> `direction` (direction)

>   If `side-axis` is `0` (or `X`), then this property determines whether the object is placed `LEFT`, `CENTER` or `RIGHT` with respect to the other object. Otherwise, it determines whether the object is placed `UP`, `CENTER` or `DOWN`. Numerical values may also be used: `UP`=`1`, `DOWN`=`-1`, `LEFT`=`-1`, `RIGHT`=`1`, `CENTER`=`0`.

> `double-stem-separation` (number)

>   The distance between the two stems of a half note in tablature when using `\tabFullNotation`, not counting the width of the stems themselves, expressed as a multiple of the default height of a staff-space in the traditional five-line staff.

> `duration-log` (integer)

>   The 2-log of the note head duration, i.e., `0` = whole note, `1` = half note, etc.

> `french-beaming` (boolean)

>   Use French beaming style for this stem. The stem stops at the innermost beams.

> `length` (dimension, in staff space)

>   User override for the stem length of unbeamed stems (each unit represents half a `staff-space`).

> `length-fraction` (number)

>   Multiplier for lengths. Used for determining ledger lines and stem lengths.

> `max-beam-connect` (integer)

>   Maximum number of beams to connect to beams from this stem. Further beams are typeset as beamlets.

> `neutral-direction` (direction)

>   Which direction to take in the center of the staff.

> `no-stem-extend` (boolean)

>   If set, notes with ledger lines do not get stems extending to the middle staff line.

> `note-collision-threshold` (dimension, in staff space)

>   Simultaneous notes that are this close or closer in units of `staff-space` will be identified as vertically colliding. Used by `Stem` grobs for notes in the same voice, and `NoteCollision` grobs for notes in different voices. Default value 1.

> `stem-begin-position` (number)

>   User override for the begin position of a stem.

> `stemlet-length` (number)

>   How long should be a stem over a rest?

> `thickness` (number)

>   For grobs made up of lines, this is the thickness of the line. For slurs and ties, this is the distance between the two arcs of the curve’s outline at its thickest point, not counting the diameter of the virtual “pen” that draws the arcs. This property is expressed as a multiple of the current staff-line thickness (i.e., the visual output is influenced by changes to `Staff.StaffSymbol.thickness`).

#### Internal properties:

> `beam` (graphical (layout) object)

>   A pointer to the beam, if applicable.

> `flag` (graphical (layout) object)

>   A pointer to a `Flag` object.

> `french-beaming-stem-adjustment` (dimension, in staff space)

>   Stem will be shortened by this amount of space in case of French beaming style.

> `melody-spanner` (graphical (layout) object)

>   The `MelodyItem` object for a stem.

> `note-heads` (array of grobs)

>   An array of note head grobs.

> `positioning-done` (boolean)

>   Used to signal that a positioning element did its job. This ensures that a positioning is only done once.

> `rests` (array of grobs)

>   An array of rest objects.

> `stem-info` (pair)

>   A cache of stem parameters.

> `tremolo-flag` (graphical (layout) object)

>   The tremolo object on a stem.

This grob interface is used in the following graphical object(s): `Stem`.

#### LilyPond Internals Reference v2.26.0 (stable-branch).

- 1 Music definitions
  - 1.1 Music expressions
    - 1.1.1 `AbsoluteDynamicEvent`
    - 1.1.2 `AdHocJumpEvent`
    - 1.1.3 `AdHocMarkEvent`
    - 1.1.4 `AlternativeEvent`
    - 1.1.5 `AnnotateOutputEvent`
    - 1.1.6 `ApplyContext`
    - 1.1.7 `ApplyOutputEvent`
    - 1.1.8 `ArpeggioEvent`
    - 1.1.9 `ArticulationEvent`
    - 1.1.10 `BarCheckEvent`
    - 1.1.11 `BarEvent`
    - 1.1.12 `BassFigureEvent`
    - 1.1.13 `BeamEvent`
    - 1.1.14 `BeamForbidEvent`
    - 1.1.15 `BendAfterEvent`
    - 1.1.16 `BendSpanEvent`
    - 1.1.17 `BreakDynamicSpanEvent`
    - 1.1.18 `BreathingEvent`
    - 1.1.19 `CaesuraEvent`
    - 1.1.20 `ChordSlurEvent`
    - 1.1.21 `ClusterNoteEvent`
    - 1.1.22 `CodaMarkEvent`
    - 1.1.23 `CompletizeExtenderEvent`
    - 1.1.24 `ContextChange`
    - 1.1.25 `ContextSpeccedMusic`
    - 1.1.26 `CrescendoEvent`
    - 1.1.27 `DalSegnoEvent`
    - 1.1.28 `DecrescendoEvent`
    - 1.1.29 `DoublePercentEvent`
    - 1.1.30 `DurationLineEvent`
    - 1.1.31 `EpisemaEvent`
    - 1.1.32 `Event`
    - 1.1.33 `EventChord`
    - 1.1.34 `ExtenderEvent`
    - 1.1.35 `FineEvent`
    - 1.1.36 `FingerGlideEvent`
    - 1.1.37 `FingeringEvent`
    - 1.1.38 `FootnoteEvent`
    - 1.1.39 `GlissandoEvent`
    - 1.1.40 `GraceMusic`
    - 1.1.41 `HarmonicEvent`
    - 1.1.42 `HyphenEvent`
    - 1.1.43 `InitialContextMusic`
    - 1.1.44 `KeyChangeEvent`
    - 1.1.45 `LabelEvent`
    - 1.1.46 `LaissezVibrerEvent`
    - 1.1.47 `LigatureEvent`
    - 1.1.48 `LineBreakEvent`
    - 1.1.49 `LyricCombineMusic`
    - 1.1.50 `LyricEvent`
    - 1.1.51 `MeasureCounterEvent`
    - 1.1.52 `MeasureSpannerEvent`
    - 1.1.53 `MultiMeasureArticulationEvent`
    - 1.1.54 `MultiMeasureRestEvent`
    - 1.1.55 `MultiMeasureRestMusic`
    - 1.1.56 `MultiMeasureTextEvent`
    - 1.1.57 `Music`
    - 1.1.58 `NonArpeggiatoEvent`
    - 1.1.59 `NoteEvent`
    - 1.1.60 `NoteGroupingEvent`
    - 1.1.61 `OptionalMaterialEvent`
    - 1.1.62 `OttavaEvent`
    - 1.1.63 `OverrideProperty`
    - 1.1.64 `PageBreakEvent`
    - 1.1.65 `PageTurnEvent`
    - 1.1.66 `PartCombineEvent`
    - 1.1.67 `PartCombineMusic`
    - 1.1.68 `PartialEvent`
    - 1.1.69 `PartialSet`
    - 1.1.70 `PercentEvent`
    - 1.1.71 `PercentRepeatedMusic`
    - 1.1.72 `PesOrFlexaEvent`
    - 1.1.73 `PhrasingSlurEvent`
    - 1.1.74 `PolymetricTimeSignatureEvent`
    - 1.1.75 `PolymetricTimeSignatureMusic`
    - 1.1.76 `PostEvents`
    - 1.1.77 `PropertySet`
    - 1.1.78 `PropertyUnset`
    - 1.1.79 `QuoteMusic`
    - 1.1.80 `ReferenceTimeSignatureEvent`
    - 1.1.81 `ReferenceTimeSignatureMusic`
    - 1.1.82 `RehearsalMarkEvent`
    - 1.1.83 `RelativeOctaveCheck`
    - 1.1.84 `RelativeOctaveMusic`
    - 1.1.85 `RepeatSlashEvent`
    - 1.1.86 `RepeatTieEvent`
    - 1.1.87 `RestEvent`
    - 1.1.88 `RevertProperty`
    - 1.1.89 `ScriptEvent`
    - 1.1.90 `SectionEvent`
    - 1.1.91 `SectionLabelEvent`
    - 1.1.92 `SegnoMarkEvent`
    - 1.1.93 `SegnoRepeatedMusic`
    - 1.1.94 `SequentialAlternativeMusic`
    - 1.1.95 `SequentialMusic`
    - 1.1.96 `SimultaneousMusic`
    - 1.1.97 `SkipEvent`
    - 1.1.98 `SkipMusic`
    - 1.1.99 `SkippedMusic`
    - 1.1.100 `SlurEvent`
    - 1.1.101 `SostenutoEvent`
    - 1.1.102 `SpacingSectionEvent`
    - 1.1.103 `SpanEvent`
    - 1.1.104 `StaffHighlightEvent`
    - 1.1.105 `StaffSpanEvent`
    - 1.1.106 `StringNumberEvent`
    - 1.1.107 `StrokeFingerEvent`
    - 1.1.108 `SustainEvent`
    - 1.1.109 `TempoChangeEvent`
    - 1.1.110 `TextMarkEvent`
    - 1.1.111 `TextScriptEvent`
    - 1.1.112 `TextSpanEvent`
    - 1.1.113 `TieEvent`
    - 1.1.114 `TimeScaledMusic`
    - 1.1.115 `TransposedMusic`
    - 1.1.116 `TremoloEvent`
    - 1.1.117 `TremoloRepeatedMusic`
    - 1.1.118 `TremoloSpanEvent`
    - 1.1.119 `TrillSpanEvent`
    - 1.1.120 `TupletSpanEvent`
    - 1.1.121 `UnaCordaEvent`
    - 1.1.122 `UnfoldedRepeatedMusic`
    - 1.1.123 `UnfoldedSpeccedMusic`
    - 1.1.124 `UnrelativableMusic`
    - 1.1.125 `VoiceSeparator`
    - 1.1.126 `VoltaRepeatEndEvent`
    - 1.1.127 `VoltaRepeatStartEvent`
    - 1.1.128 `VoltaRepeatedMusic`
    - 1.1.129 `VoltaSpanEvent`
    - 1.1.130 `VoltaSpeccedMusic`
    - 1.1.131 `VowelTransitionEvent`
  - 1.2 Music classes
    - 1.2.1 `absolute-dynamic-event`
    - 1.2.2 `ad-hoc-jump-event`
    - 1.2.3 `ad-hoc-mark-event`
    - 1.2.4 `alternative-event`
    - 1.2.5 `annotate-output-event`
    - 1.2.6 `apply-output-event`
    - 1.2.7 `arpeggio-event`
    - 1.2.8 `articulation-event`
    - 1.2.9 `bar-check-event`
    - 1.2.10 `bar-event`
    - 1.2.11 `bass-figure-event`
    - 1.2.12 `beam-event`
    - 1.2.13 `beam-forbid-event`
    - 1.2.14 `bend-after-event`
    - 1.2.15 `bend-span-event`
    - 1.2.16 `break-dynamic-span-event`
    - 1.2.17 `break-event`
    - 1.2.18 `break-span-event`
    - 1.2.19 `breathing-event`
    - 1.2.20 `caesura-event`
    - 1.2.21 `chord-slur-event`
    - 1.2.22 `cluster-note-event`
    - 1.2.23 `coda-mark-event`
    - 1.2.24 `completize-extender-event`
    - 1.2.25 `crescendo-event`
    - 1.2.26 `dal-segno-event`
    - 1.2.27 `decrescendo-event`
    - 1.2.28 `double-percent-event`
    - 1.2.29 `duration-line-event`
    - 1.2.30 `dynamic-event`
    - 1.2.31 `episema-event`
    - 1.2.32 `extender-event`
    - 1.2.33 `fine-event`
    - 1.2.34 `finger-glide-event`
    - 1.2.35 `fingering-event`
    - 1.2.36 `footnote-event`
    - 1.2.37 `general-rest-event`
    - 1.2.38 `glissando-event`
    - 1.2.39 `harmonic-event`
    - 1.2.40 `hyphen-event`
    - 1.2.41 `key-change-event`
    - 1.2.42 `label-event`
    - 1.2.43 `laissez-vibrer-event`
    - 1.2.44 `layout-instruction-event`
    - 1.2.45 `ligature-event`
    - 1.2.46 `line-break-event`
    - 1.2.47 `lyric-event`
    - 1.2.48 `mark-event`
    - 1.2.49 `measure-counter-event`
    - 1.2.50 `measure-spanner-event`
    - 1.2.51 `melodic-event`
    - 1.2.52 `multi-measure-articulation-event`
    - 1.2.53 `multi-measure-rest-event`
    - 1.2.54 `multi-measure-text-event`
    - 1.2.55 `music-event`
    - 1.2.56 `non-arpeggiato-event`
    - 1.2.57 `note-event`
    - 1.2.58 `note-grouping-event`
    - 1.2.59 `optional-material-event`
    - 1.2.60 `ottava-event`
    - 1.2.61 `page-break-event`
    - 1.2.62 `page-turn-event`
    - 1.2.63 `part-combine-event`
    - 1.2.64 `partial-event`
    - 1.2.65 `pedal-event`
    - 1.2.66 `percent-event`
    - 1.2.67 `pes-or-flexa-event`
    - 1.2.68 `phrasing-slur-event`
    - 1.2.69 `polymetric-time-signature-event`
    - 1.2.70 `reference-time-signature-event`
    - 1.2.71 `rehearsal-mark-event`
    - 1.2.72 `repeat-slash-event`
    - 1.2.73 `repeat-tie-event`
    - 1.2.74 `rest-event`
    - 1.2.75 `rhythmic-event`
    - 1.2.76 `script-event`
    - 1.2.77 `section-event`
    - 1.2.78 `section-label-event`
    - 1.2.79 `segno-mark-event`
    - 1.2.80 `skip-event`
    - 1.2.81 `slur-event`
    - 1.2.82 `sostenuto-event`
    - 1.2.83 `spacing-section-event`
    - 1.2.84 `span-dynamic-event`
    - 1.2.85 `span-event`
    - 1.2.86 `staff-highlight-event`
    - 1.2.87 `staff-span-event`
    - 1.2.88 `StreamEvent`
    - 1.2.89 `string-number-event`
    - 1.2.90 `stroke-finger-event`
    - 1.2.91 `structural-event`
    - 1.2.92 `sustain-event`
    - 1.2.93 `tempo-change-event`
    - 1.2.94 `text-mark-event`
    - 1.2.95 `text-script-event`
    - 1.2.96 `text-span-event`
    - 1.2.97 `tie-event`
    - 1.2.98 `time-signature-event`
    - 1.2.99 `tremolo-event`
    - 1.2.100 `tremolo-span-event`
    - 1.2.101 `trill-span-event`
    - 1.2.102 `tuplet-span-event`
    - 1.2.103 `una-corda-event`
    - 1.2.104 `volta-repeat-end-event`
    - 1.2.105 `volta-repeat-start-event`
    - 1.2.106 `volta-span-event`
    - 1.2.107 `vowel-transition-event`
  - 1.3 Music properties
- 2 Translation
  - 2.1 Contexts
    - 2.1.1 `ChoirStaff`
    - 2.1.2 `ChordGrid`
    - 2.1.3 `ChordGridScore`
    - 2.1.4 `ChordNames`
    - 2.1.5 `CueVoice`
    - 2.1.6 `Devnull`
    - 2.1.7 `DrumStaff`
    - 2.1.8 `DrumVoice`
    - 2.1.9 `Dynamics`
    - 2.1.10 `FiguredBass`
    - 2.1.11 `FretBoards`
    - 2.1.12 `Global`
    - 2.1.13 `GrandStaff`
    - 2.1.14 `GregorianTranscriptionLyrics`
    - 2.1.15 `GregorianTranscriptionStaff`
    - 2.1.16 `GregorianTranscriptionVoice`
    - 2.1.17 `InternalGregorianStaff`
    - 2.1.18 `InternalMensuralStaff`
    - 2.1.19 `KievanStaff`
    - 2.1.20 `KievanVoice`
    - 2.1.21 `Lyrics`
    - 2.1.22 `MensuralStaff`
    - 2.1.23 `MensuralVoice`
    - 2.1.24 `NoteNames`
    - 2.1.25 `NullVoice`
    - 2.1.26 `OneStaff`
    - 2.1.27 `PetrucciStaff`
    - 2.1.28 `PetrucciVoice`
    - 2.1.29 `PianoStaff`
    - 2.1.30 `RhythmicStaff`
    - 2.1.31 `Score`
    - 2.1.32 `Staff`
    - 2.1.33 `StaffGroup`
    - 2.1.34 `StandaloneRhythmScore`
    - 2.1.35 `StandaloneRhythmStaff`
    - 2.1.36 `StandaloneRhythmVoice`
    - 2.1.37 `TabStaff`
    - 2.1.38 `TabVoice`
    - 2.1.39 `VaticanaLyrics`
    - 2.1.40 `VaticanaScore`
    - 2.1.41 `VaticanaStaff`
    - 2.1.42 `VaticanaVoice`
    - 2.1.43 `Voice`
  - 2.2 Engravers and Performers
    - 2.2.1 `Accidental_engraver`
    - 2.2.2 `Alteration_glyph_engraver`
    - 2.2.3 `Ambitus_engraver`
    - 2.2.4 `Apply_output_engraver`
    - 2.2.5 `Arpeggio_engraver`
    - 2.2.6 `Auto_beam_engraver`
    - 2.2.7 `Axis_group_engraver`
    - 2.2.8 `Balloon_engraver`
    - 2.2.9 `Bar_engraver`
    - 2.2.10 `Bar_number_engraver`
    - 2.2.11 `Beam_collision_engraver`
    - 2.2.12 `Beam_engraver`
    - 2.2.13 `Beam_performer`
    - 2.2.14 `Beat_engraver`
    - 2.2.15 `Beat_performer`
    - 2.2.16 `Bend_engraver`
    - 2.2.17 `Bend_spanner_engraver`
    - 2.2.18 `Break_align_engraver`
    - 2.2.19 `Breathing_sign_engraver`
    - 2.2.20 `Caesura_engraver`
    - 2.2.21 `Centered_bar_number_align_engraver`
    - 2.2.22 `Chord_name_engraver`
    - 2.2.23 `Chord_square_engraver`
    - 2.2.24 `Chord_tremolo_engraver`
    - 2.2.25 `Clef_engraver`
    - 2.2.26 `Cluster_spanner_engraver`
    - 2.2.27 `Collision_engraver`
    - 2.2.28 `Completion_heads_engraver`
    - 2.2.29 `Completion_rest_engraver`
    - 2.2.30 `Concurrent_hairpin_engraver`
    - 2.2.31 `Control_track_performer`
    - 2.2.32 `Cue_clef_engraver`
    - 2.2.33 `Current_chord_text_engraver`
    - 2.2.34 `Custos_engraver`
    - 2.2.35 `Divisio_engraver`
    - 2.2.36 `Dot_column_engraver`
    - 2.2.37 `Dots_engraver`
    - 2.2.38 `Double_percent_repeat_engraver`
    - 2.2.39 `Drum_note_performer`
    - 2.2.40 `Drum_notes_engraver`
    - 2.2.41 `Duration_line_engraver`
    - 2.2.42 `Dynamic_align_engraver`
    - 2.2.43 `Dynamic_engraver`
    - 2.2.44 `Dynamic_performer`
    - 2.2.45 `Episema_engraver`
    - 2.2.46 `Extender_engraver`
    - 2.2.47 `Figured_bass_engraver`
    - 2.2.48 `Figured_bass_position_engraver`
    - 2.2.49 `Finger_glide_engraver`
    - 2.2.50 `Fingering_column_engraver`
    - 2.2.51 `Fingering_engraver`
    - 2.2.52 `Font_size_engraver`
    - 2.2.53 `Footnote_engraver`
    - 2.2.54 `Forbid_line_break_engraver`
    - 2.2.55 `Fretboard_engraver`
    - 2.2.56 `Glissando_engraver`
    - 2.2.57 `Grace_auto_beam_engraver`
    - 2.2.58 `Grace_beam_engraver`
    - 2.2.59 `Grace_engraver`
    - 2.2.60 `Grace_spacing_engraver`
    - 2.2.61 `Grid_chord_name_engraver`
    - 2.2.62 `Grid_line_span_engraver`
    - 2.2.63 `Grid_point_engraver`
    - 2.2.64 `Grob_pq_engraver`
    - 2.2.65 `Horizontal_bracket_engraver`
    - 2.2.66 `Horizontal_script_engraver`
    - 2.2.67 `Hyphen_engraver`
    - 2.2.68 `Instrument_name_engraver`
    - 2.2.69 `Instrument_switch_engraver`
    - 2.2.70 `Jump_engraver`
    - 2.2.71 `Keep_alive_together_engraver`
    - 2.2.72 `Key_engraver`
    - 2.2.73 `Key_performer`
    - 2.2.74 `Kievan_ligature_engraver`
    - 2.2.75 `Laissez_vibrer_engraver`
    - 2.2.76 `Ledger_line_engraver`
    - 2.2.77 `Ligature_bracket_engraver`
    - 2.2.78 `Lyric_engraver`
    - 2.2.79 `Lyric_performer`
    - 2.2.80 `Lyric_repeat_count_engraver`
    - 2.2.81 `Mark_engraver`
    - 2.2.82 `Mark_performer`
    - 2.2.83 `Mark_tracking_translator`
    - 2.2.84 `Measure_counter_engraver`
    - 2.2.85 `Measure_grouping_engraver`
    - 2.2.86 `Measure_spanner_engraver`
    - 2.2.87 `Melody_engraver`
    - 2.2.88 `Mensural_ligature_engraver`
    - 2.2.89 `Merge_mmrest_numbers_engraver`
    - 2.2.90 `Merge_rests_engraver`
    - 2.2.91 `Metronome_mark_engraver`
    - 2.2.92 `Midi_control_change_performer`
    - 2.2.93 `Multi_measure_rest_engraver`
    - 2.2.94 `New_fingering_engraver`
    - 2.2.95 `Non_musical_script_column_engraver`
    - 2.2.96 `Note_head_line_engraver`
    - 2.2.97 `Note_heads_engraver`
    - 2.2.98 `Note_name_engraver`
    - 2.2.99 `Note_performer`
    - 2.2.100 `Note_spacing_engraver`
    - 2.2.101 `Optional_material_bracket_engraver`
    - 2.2.102 `Ottava_spanner_engraver`
    - 2.2.103 `Page_turn_engraver`
    - 2.2.104 `Paper_column_engraver`
    - 2.2.105 `Parenthesis_engraver`
    - 2.2.106 `Part_combine_engraver`
    - 2.2.107 `Percent_repeat_engraver`
    - 2.2.108 `Phrasing_slur_engraver`
    - 2.2.109 `Piano_pedal_align_engraver`
    - 2.2.110 `Piano_pedal_engraver`
    - 2.2.111 `Piano_pedal_performer`
    - 2.2.112 `Pitch_squash_engraver`
    - 2.2.113 `Pitched_trill_engraver`
    - 2.2.114 `Pure_from_neighbor_engraver`
    - 2.2.115 `Repeat_acknowledge_engraver`
    - 2.2.116 `Repeat_tie_engraver`
    - 2.2.117 `Rest_collision_engraver`
    - 2.2.118 `Rest_engraver`
    - 2.2.119 `Rhythmic_column_engraver`
    - 2.2.120 `Script_column_engraver`
    - 2.2.121 `Script_engraver`
    - 2.2.122 `Script_row_engraver`
    - 2.2.123 `Separating_line_group_engraver`
    - 2.2.124 `Show_control_points_engraver`
    - 2.2.125 `Signum_repetitionis_engraver`
    - 2.2.126 `Skip_typesetting_engraver`
    - 2.2.127 `Slash_repeat_engraver`
    - 2.2.128 `Slur_engraver`
    - 2.2.129 `Slur_performer`
    - 2.2.130 `Spacing_engraver`
    - 2.2.131 `Span_arpeggio_engraver`
    - 2.2.132 `Span_bar_engraver`
    - 2.2.133 `Span_bar_stub_engraver`
    - 2.2.134 `Span_stem_engraver`
    - 2.2.135 `Spanner_break_forbid_engraver`
    - 2.2.136 `Spanner_tracking_engraver`
    - 2.2.137 `Staff_collecting_engraver`
    - 2.2.138 `Staff_highlight_engraver`
    - 2.2.139 `Staff_performer`
    - 2.2.140 `Staff_symbol_engraver`
    - 2.2.141 `Stanza_number_align_engraver`
    - 2.2.142 `Stanza_number_engraver`
    - 2.2.143 `Stem_engraver`
    - 2.2.144 `System_start_delimiter_engraver`
    - 2.2.145 `Tab_note_heads_engraver`
    - 2.2.146 `Tab_staff_symbol_engraver`
    - 2.2.147 `Tab_tie_follow_engraver`
    - 2.2.148 `Tempo_performer`
    - 2.2.149 `Text_engraver`
    - 2.2.150 `Text_mark_engraver`
    - 2.2.151 `Text_spanner_engraver`
    - 2.2.152 `Tie_engraver`
    - 2.2.153 `Tie_performer`
    - 2.2.154 `Time_signature_engraver`
    - 2.2.155 `Time_signature_performer`
    - 2.2.156 `Timing_translator`
    - 2.2.157 `Toe_heel_engraver`
    - 2.2.158 `Trill_spanner_engraver`
    - 2.2.159 `Tuplet_engraver`
    - 2.2.160 `Tweak_engraver`
    - 2.2.161 `Vaticana_ligature_engraver`
    - 2.2.162 `Vertical_align_engraver`
    - 2.2.163 `Volta_engraver`
  - 2.3 Tunable context properties
  - 2.4 Internal context properties
- 3 Backend
  - 3.1 All layout objects
    - 3.1.1 `Accidental`
    - 3.1.2 `AccidentalCautionary`
    - 3.1.3 `AccidentalPlacement`
    - 3.1.4 `AccidentalSuggestion`
    - 3.1.5 `Ambitus`
    - 3.1.6 `AmbitusAccidental`
    - 3.1.7 `AmbitusLine`
    - 3.1.8 `AmbitusNoteHead`
    - 3.1.9 `ApproximatePitchNoteHead`
    - 3.1.10 `Arpeggio`
    - 3.1.11 `BalloonText`
    - 3.1.12 `BarLine`
    - 3.1.13 `BarNumber`
    - 3.1.14 `BassFigure`
    - 3.1.15 `BassFigureAlignment`
    - 3.1.16 `BassFigureAlignmentPositioning`
    - 3.1.17 `BassFigureBracket`
    - 3.1.18 `BassFigureContinuation`
    - 3.1.19 `BassFigureLine`
    - 3.1.20 `Beam`
    - 3.1.21 `BendAfter`
    - 3.1.22 `BendSpanner`
    - 3.1.23 `BreakAlignGroup`
    - 3.1.24 `BreakAlignment`
    - 3.1.25 `BreathingSign`
    - 3.1.26 `CaesuraScript`
    - 3.1.27 `CenteredBarNumber`
    - 3.1.28 `CenteredBarNumberLineSpanner`
    - 3.1.29 `ChordBracket`
    - 3.1.30 `ChordName`
    - 3.1.31 `ChordSlur`
    - 3.1.32 `ChordSquare`
    - 3.1.33 `Clef`
    - 3.1.34 `ClefModifier`
    - 3.1.35 `ClusterSpanner`
    - 3.1.36 `ClusterSpannerBeacon`
    - 3.1.37 `CodaMark`
    - 3.1.38 `CombineTextScript`
    - 3.1.39 `ControlPoint`
    - 3.1.40 `ControlPolygon`
    - 3.1.41 `CueClef`
    - 3.1.42 `CueEndClef`
    - 3.1.43 `Custos`
    - 3.1.44 `Divisio`
    - 3.1.45 `DotColumn`
    - 3.1.46 `Dots`
    - 3.1.47 `DoublePercentRepeat`
    - 3.1.48 `DoublePercentRepeatCounter`
    - 3.1.49 `DoubleRepeatSlash`
    - 3.1.50 `DurationLine`
    - 3.1.51 `DynamicLineSpanner`
    - 3.1.52 `DynamicText`
    - 3.1.53 `DynamicTextSpanner`
    - 3.1.54 `Episema`
    - 3.1.55 `FingerGlideSpanner`
    - 3.1.56 `Fingering`
    - 3.1.57 `FingeringColumn`
    - 3.1.58 `Flag`
    - 3.1.59 `Footnote`
    - 3.1.60 `FretBoard`
    - 3.1.61 `Glissando`
    - 3.1.62 `GraceSpacing`
    - 3.1.63 `GridChordName`
    - 3.1.64 `GridLine`
    - 3.1.65 `GridPoint`
    - 3.1.66 `Hairpin`
    - 3.1.67 `HorizontalBracket`
    - 3.1.68 `HorizontalBracketText`
    - 3.1.69 `InstrumentName`
    - 3.1.70 `InstrumentSwitch`
    - 3.1.71 `JumpScript`
    - 3.1.72 `KeyCancellation`
    - 3.1.73 `KeySignature`
    - 3.1.74 `KievanLigature`
    - 3.1.75 `LaissezVibrerTie`
    - 3.1.76 `LaissezVibrerTieColumn`
    - 3.1.77 `LedgerLineSpanner`
    - 3.1.78 `LeftEdge`
    - 3.1.79 `LigatureBracket`
    - 3.1.80 `LyricExtender`
    - 3.1.81 `LyricHyphen`
    - 3.1.82 `LyricRepeatCount`
    - 3.1.83 `LyricSpace`
    - 3.1.84 `LyricText`
    - 3.1.85 `MeasureCounter`
    - 3.1.86 `MeasureGrouping`
    - 3.1.87 `MeasureSpanner`
    - 3.1.88 `MelodyItem`
    - 3.1.89 `MensuralLigature`
    - 3.1.90 `MetronomeMark`
    - 3.1.91 `MultiMeasureRest`
    - 3.1.92 `MultiMeasureRestNumber`
    - 3.1.93 `MultiMeasureRestScript`
    - 3.1.94 `MultiMeasureRestText`
    - 3.1.95 `NonMusicalPaperColumn`
    - 3.1.96 `NoteCollision`
    - 3.1.97 `NoteColumn`
    - 3.1.98 `NoteHead`
    - 3.1.99 `NoteName`
    - 3.1.100 `NoteSpacing`
    - 3.1.101 `OptionalMaterialBracket`
    - 3.1.102 `OttavaBracket`
    - 3.1.103 `PaperColumn`
    - 3.1.104 `Parentheses`
    - 3.1.105 `PercentRepeat`
    - 3.1.106 `PercentRepeatCounter`
    - 3.1.107 `PhrasingSlur`
    - 3.1.108 `PianoPedalBracket`
    - 3.1.109 `RehearsalMark`
    - 3.1.110 `RepeatSlash`
    - 3.1.111 `RepeatTie`
    - 3.1.112 `RepeatTieColumn`
    - 3.1.113 `Rest`
    - 3.1.114 `RestCollision`
    - 3.1.115 `Script`
    - 3.1.116 `ScriptColumn`
    - 3.1.117 `ScriptRow`
    - 3.1.118 `SectionLabel`
    - 3.1.119 `SegnoMark`
    - 3.1.120 `SignumRepetitionis`
    - 3.1.121 `Slur`
    - 3.1.122 `SostenutoPedal`
    - 3.1.123 `SostenutoPedalLineSpanner`
    - 3.1.124 `SpacingSpanner`
    - 3.1.125 `SpanBar`
    - 3.1.126 `SpanBarStub`
    - 3.1.127 `StaffEllipsis`
    - 3.1.128 `StaffGrouper`
    - 3.1.129 `StaffHighlight`
    - 3.1.130 `StaffSpacing`
    - 3.1.131 `StaffSymbol`
    - 3.1.132 `StanzaNumber`
    - 3.1.133 `Stem`
    - 3.1.134 `StemStub`
    - 3.1.135 `StemTremolo`
    - 3.1.136 `StringNumber`
    - 3.1.137 `StrokeFinger`
    - 3.1.138 `SustainPedal`
    - 3.1.139 `SustainPedalLineSpanner`
    - 3.1.140 `System`
    - 3.1.141 `SystemStartBar`
    - 3.1.142 `SystemStartBrace`
    - 3.1.143 `SystemStartBracket`
    - 3.1.144 `SystemStartSquare`
    - 3.1.145 `TabNoteHead`
    - 3.1.146 `TextMark`
    - 3.1.147 `TextScript`
    - 3.1.148 `TextSpanner`
    - 3.1.149 `Tie`
    - 3.1.150 `TieColumn`
    - 3.1.151 `TimeSignature`
    - 3.1.152 `TrillPitchAccidental`
    - 3.1.153 `TrillPitchGroup`
    - 3.1.154 `TrillPitchHead`
    - 3.1.155 `TrillPitchParentheses`
    - 3.1.156 `TrillSpanner`
    - 3.1.157 `TupletBracket`
    - 3.1.158 `TupletNumber`
    - 3.1.159 `UnaCordaPedal`
    - 3.1.160 `UnaCordaPedalLineSpanner`
    - 3.1.161 `VaticanaLigature`
    - 3.1.162 `VerticalAlignment`
    - 3.1.163 `VerticalAxisGroup`
    - 3.1.164 `VoiceFollower`
    - 3.1.165 `VoltaBracket`
    - 3.1.166 `VoltaBracketSpanner`
    - 3.1.167 `VowelTransition`
  - 3.2 Graphical Object Interfaces
    - 3.2.1 `accidental-interface`
    - 3.2.2 `accidental-participating-head-interface`
    - 3.2.3 `accidental-placement-interface`
    - 3.2.4 `accidental-suggestion-interface`
    - 3.2.5 `accidental-switch-interface`
    - 3.2.6 `align-interface`
    - 3.2.7 `ambitus-interface`
    - 3.2.8 `arpeggio-interface`
    - 3.2.9 `axis-group-interface`
    - 3.2.10 `balloon-interface`
    - 3.2.11 `bar-line-interface`
    - 3.2.12 `bar-number-interface`
    - 3.2.13 `bass-figure-alignment-interface`
    - 3.2.14 `bass-figure-interface`
    - 3.2.15 `beam-interface`
    - 3.2.16 `bend-after-interface`
    - 3.2.17 `bend-interface`
    - 3.2.18 `bezier-curve-interface`
    - 3.2.19 `break-alignable-interface`
    - 3.2.20 `break-aligned-interface`
    - 3.2.21 `break-alignment-interface`
    - 3.2.22 `breathing-sign-interface`
    - 3.2.23 `caesura-script-interface`
    - 3.2.24 `centered-bar-number-interface`
    - 3.2.25 `centered-bar-number-line-spanner-interface`
    - 3.2.26 `centered-spanner-interface`
    - 3.2.27 `chord-bracket-interface`
    - 3.2.28 `chord-name-interface`
    - 3.2.29 `chord-slur-interface`
    - 3.2.30 `chord-square-interface`
    - 3.2.31 `clef-interface`
    - 3.2.32 `clef-modifier-interface`
    - 3.2.33 `cluster-beacon-interface`
    - 3.2.34 `cluster-interface`
    - 3.2.35 `coda-mark-interface`
    - 3.2.36 `control-point-interface`
    - 3.2.37 `control-polygon-interface`
    - 3.2.38 `custos-interface`
    - 3.2.39 `dot-column-interface`
    - 3.2.40 `dots-interface`
    - 3.2.41 `duration-line-interface`
    - 3.2.42 `dynamic-interface`
    - 3.2.43 `dynamic-line-spanner-interface`
    - 3.2.44 `dynamic-text-interface`
    - 3.2.45 `dynamic-text-spanner-interface`
    - 3.2.46 `enclosing-bracket-interface`
    - 3.2.47 `episema-interface`
    - 3.2.48 `figured-bass-continuation-interface`
    - 3.2.49 `finger-glide-interface`
    - 3.2.50 `finger-interface`
    - 3.2.51 `fingering-column-interface`
    - 3.2.52 `flag-interface`
    - 3.2.53 `font-interface`
    - 3.2.54 `footnote-interface`
    - 3.2.55 `fret-diagram-interface`
    - 3.2.56 `glissando-interface`
    - 3.2.57 `grace-spacing-interface`
    - 3.2.58 `gregorian-ligature-interface`
    - 3.2.59 `grid-chord-name-interface`
    - 3.2.60 `grid-line-interface`
    - 3.2.61 `grid-point-interface`
    - 3.2.62 `grob-interface`
    - 3.2.63 `hairpin-interface`
    - 3.2.64 `hara-kiri-group-spanner-interface`
    - 3.2.65 `horizontal-bracket-interface`
    - 3.2.66 `horizontal-bracket-text-interface`
    - 3.2.67 `horizontal-line-spanner-interface`
    - 3.2.68 `inline-accidental-interface`
    - 3.2.69 `instrument-specific-markup-interface`
    - 3.2.70 `item-interface`
    - 3.2.71 `jump-script-interface`
    - 3.2.72 `key-cancellation-interface`
    - 3.2.73 `key-signature-interface`
    - 3.2.74 `kievan-ligature-interface`
    - 3.2.75 `ledger-line-spanner-interface`
    - 3.2.76 `ledgered-grob-interface`
    - 3.2.77 `ledgered-interface`
    - 3.2.78 `ligature-bracket-interface`
    - 3.2.79 `ligature-head-interface`
    - 3.2.80 `ligature-interface`
    - 3.2.81 `line-interface`
    - 3.2.82 `line-spanner-interface`
    - 3.2.83 `lyric-extender-interface`
    - 3.2.84 `lyric-hyphen-interface`
    - 3.2.85 `lyric-interface`
    - 3.2.86 `lyric-repeat-count-interface`
    - 3.2.87 `lyric-space-interface`
    - 3.2.88 `lyric-syllable-interface`
    - 3.2.89 `mark-interface`
    - 3.2.90 `measure-counter-interface`
    - 3.2.91 `measure-grouping-interface`
    - 3.2.92 `measure-spanner-interface`
    - 3.2.93 `melody-spanner-interface`
    - 3.2.94 `mensural-ligature-interface`
    - 3.2.95 `metronome-mark-interface`
    - 3.2.96 `multi-measure-interface`
    - 3.2.97 `multi-measure-rest-interface`
    - 3.2.98 `multi-measure-rest-number-interface`
    - 3.2.99 `musical-paper-column-interface`
    - 3.2.100 `non-musical-paper-column-interface`
    - 3.2.101 `note-collision-interface`
    - 3.2.102 `note-column-interface`
    - 3.2.103 `note-head-interface`
    - 3.2.104 `note-name-interface`
    - 3.2.105 `note-spacing-interface`
    - 3.2.106 `number-interface`
    - 3.2.107 `optional-material-bracket-interface`
    - 3.2.108 `ottava-bracket-interface`
    - 3.2.109 `outside-staff-axis-group-interface`
    - 3.2.110 `outside-staff-interface`
    - 3.2.111 `paper-column-interface`
    - 3.2.112 `parentheses-interface`
    - 3.2.113 `passage-delimiter-interface`
    - 3.2.114 `percent-repeat-interface`
    - 3.2.115 `piano-pedal-bracket-interface`
    - 3.2.116 `piano-pedal-interface`
    - 3.2.117 `piano-pedal-script-interface`
    - 3.2.118 `pitched-trill-interface`
    - 3.2.119 `pure-from-neighbor-interface`
    - 3.2.120 `rehearsal-mark-interface`
    - 3.2.121 `rest-collision-interface`
    - 3.2.122 `rest-interface`
    - 3.2.123 `rhythmic-grob-interface`
    - 3.2.124 `rhythmic-head-interface`
    - 3.2.125 `script-column-interface`
    - 3.2.126 `script-interface`
    - 3.2.127 `section-label-interface`
    - 3.2.128 `segno-mark-interface`
    - 3.2.129 `self-alignment-interface`
    - 3.2.130 `semi-tie-column-interface`
    - 3.2.131 `semi-tie-interface`
    - 3.2.132 `separation-item-interface`
    - 3.2.133 `side-position-interface`
    - 3.2.134 `signum-repetitionis-interface`
    - 3.2.135 `slur-interface`
    - 3.2.136 `spaceable-grob-interface`
    - 3.2.137 `spacing-interface`
    - 3.2.138 `spacing-options-interface`
    - 3.2.139 `spacing-spanner-interface`
    - 3.2.140 `span-bar-interface`
    - 3.2.141 `span-bar-stub-interface`
    - 3.2.142 `spanner-interface`
    - 3.2.143 `staff-ellipsis-interface`
    - 3.2.144 `staff-grouper-interface`
    - 3.2.145 `staff-highlight-interface`
    - 3.2.146 `staff-spacing-interface`
    - 3.2.147 `staff-symbol-interface`
    - 3.2.148 `staff-symbol-referencer-interface`
    - 3.2.149 `stanza-number-interface`
    - 3.2.150 `stem-interface`
    - 3.2.151 `stem-tremolo-interface`
    - 3.2.152 `sticky-grob-interface`
    - 3.2.153 `string-number-interface`
    - 3.2.154 `stroke-finger-interface`
    - 3.2.155 `system-interface`
    - 3.2.156 `system-start-delimiter-interface`
    - 3.2.157 `system-start-text-interface`
    - 3.2.158 `tab-note-head-interface`
    - 3.2.159 `text-interface`
    - 3.2.160 `text-mark-interface`
    - 3.2.161 `text-script-interface`
    - 3.2.162 `tie-column-interface`
    - 3.2.163 `tie-interface`
    - 3.2.164 `time-signature-interface`
    - 3.2.165 `trill-pitch-accidental-interface`
    - 3.2.166 `trill-spanner-interface`
    - 3.2.167 `tuplet-bracket-interface`
    - 3.2.168 `tuplet-number-interface`
    - 3.2.169 `unbreakable-spanner-interface`
    - 3.2.170 `vaticana-ligature-interface`
    - 3.2.171 `volta-bracket-interface`
    - 3.2.172 `volta-interface`
  - 3.3 User backend properties
  - 3.4 Internal backend properties
- 4 Scheme functions
- Appendix A Indices
  - A.1 Function index