3.3 User backend properties

accidental-padding (number)

Property used by Beam to avoid accidentals in whole note tremolos.

add-stem-support (boolean)

If set, the Stem object is included in this script’s support.

after-line-breaking (boolean)

Dummy property, used to trigger callback for after-line-breaking.

align-dir (direction)

Which side to align? -1: left side, 0: around center of width, 1: right side.

allow-loose-spacing (boolean)

If set, column can be detached from main spacing.

allow-span-bar (boolean)

If false, no inter-staff bar line will be created below this bar line.

alteration (number)

Alteration numbers for accidental.

alteration-alist (association list (list of pairs))

List of (pitch . accidental) pairs for key signature.

alteration-glyph-name-alist (association list (list of pairs))

An alist of key-string pairs.

annotation-balloon (boolean)

Print the balloon around an annotation.

annotation-line (boolean)

Print the line from an annotation to the grob that it annotates.

arpeggio-direction (direction)

If set, put an arrow on the arpeggio squiggly line.

arrow-length (number)

Arrow length.

arrow-width (number)

Arrow width.

auto-knee-gap (dimension, in staff space)

If a gap is found between note heads where a horizontal beam fits and it is larger than this number, make a kneed beam.

automatically-numbered (boolean)

If set, footnotes are automatically numbered.

average-spacing-wishes (boolean)

If set, the spacing wishes are averaged over staves.

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.

avoid-scripts (boolean)

If set, a tuplet bracket avoids the scripts associated with the note heads it encompasses.

avoid-slur (symbol)

Method of handling slur collisions. Choices are inside, outside, around, and ignore. inside adjusts the slur if needed to keep the grob inside the slur. outside moves the grob vertically to the outside of the slur. around moves the grob vertically to the outside of the slur only if there is a collision. ignore does not move either. In grobs whose notational significance depends on vertical position (such as accidentals, clefs, etc.), outside and around behave like ignore.

axes (list)

List of axis numbers. In the case of alignment grobs, this should contain only one number.

bar-extent (pair of numbers)

The Y-extent of the actual bar line. This may differ from Y-extent because it does not include the dots in a repeat bar line.

base-shortest-duration (moment)

Spacing is based on the shortest notes in a piece. Normally, pieces are spaced as if notes at least as short as this are present.

baseline-skip (dimension, in staff space)

Distance between base lines of multiple lines of text.

beam-thickness (dimension, in staff space)

Beam thickness, measured in staff-space units.

beam-width (dimension, in staff space)

Width of the tremolo sign.

beamed-stem-shorten (list)

How much to shorten beamed stems, when their direction is forced. It is a list, since the value is different depending on the number of flags and beams.

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.

before-line-breaking (boolean)

Dummy property, used to trigger a callback function.

bend-me (boolean)

Decide whether this grob is bent.

between-cols (pair)

Where to attach a loose column to.

bound-details (alist, with symbols as keys)

An alist of properties for determining attachments of spanners to edges.

bound-padding (number)

The amount of padding to insert around spanner bounds.

bound-prefatory-paddings (pair of numbers)

For a highlight, the amount of padding to insert at a bound from a prefatory item that is not a bar line.

bracket-flare (pair of numbers)

A pair of numbers specifying how much edges of brackets should slant outward. Value 0.0 means straight edges.

bracket-visibility (boolean or symbol)

This controls the visibility of the tuplet bracket. Setting it to #f prevents printing of the bracket. Setting the property to if-no-beam makes it print only if there is no beam associated with this tuplet bracket.

break-align-anchor (number)

Grobs aligned to this breakable item will have their X-offsets shifted by this number. In bar lines, for example, this is used to position grobs relative to the (visual) center of the bar line.

break-align-anchor-alignment (number)

Read by ly:break-aligned-interface::calc-extent-aligned-anchor for aligning an anchor to a grob’s extent.

break-align-orders (vector)

This is a vector of 3 lists: #(end-of-line unbroken start-of-line). Each list contains break-align symbols that specify an order of breakable items (see break-alignment-interface).

For example, this places time signatures before clefs:

\override Score.BreakAlignment.break-align-orders =
  #(make-vector 3 '(left-edge
                    cue-end-clef
                    ambitus
                    breathing-sign
                    time-signature
                    clef
                    cue-clef
                    staff-bar
                    key-cancellation
                    key-signature
                    custos))
break-align-symbol (symbol)

This key is used for aligning, ordering, and spacing breakable items. See break-alignment-interface.

break-align-symbols (list)

A list of break-align symbols that determines which breakable items to align this to. If the grob selected by the first symbol in the list is invisible due to break-visibility, we will align to the next grob (and so on). Choices are listed in break-alignment-interface.

break-overshoot (pair of numbers)

A pair of numbers specifying how much a broken spanner sticks out of its bounds horizontally on the broken side(s). For broken beams and broken tuplet brackets, the bounds are given by the prefatory matter on the left and/or the rightmost column on the right. For broken horizontal brackets, the bounds are the leftmost and/or rightmost column; for broken measure spanners, the left and/or right edge of the staff.

break-visibility (vector)

A vector of 3 booleans, #(end-of-line unbroken begin-of-line). #t means visible, #f means killed.

breakable (boolean)

Allow breaks here.

broken-bound-padding (number)

The amount of padding to insert when a spanner is broken at a line break.

chord-dots-limit (integer)

Limits the column of dots on each chord to the height of the chord plus chord-dots-limit staff positions.

circled-tip (boolean)

Put a circle at start/end of hairpins (al/del niente).

clef-alignments (alist, with symbols as keys)

An alist of parent-alignments that should be used for clef modifiers with various clefs

clip-edges (boolean)

Allow outward pointing beamlets at the edges of beams?

collapse-height (dimension, in staff space)

Minimum height of system start delimiter. If equal or smaller, the bracket/brace/line is removed.

collision-interfaces (list)

A list of interfaces for which automatic beam-collision resolution is run.

collision-voice-only (boolean)

Does automatic beam collsion apply only to the voice in which the beam was created?

color (color)

The color of this grob.

common-shortest-duration (moment)

The most common shortest note length. This is used in spacing. Enlarging this sets the score tighter.

concaveness (number)

A beam is concave if its inner stems are closer to the beam than the two outside stems. This number is a measure of the closeness of the inner stems. It is used for damping the slope of the beam.

connect-to-neighbor (pair)

Pair of booleans, indicating whether this grob looks as a continued break.

control-points (list of number pairs)

List of offsets (number pairs) that form control points for the tie, slur, or bracket shape. For Béziers, this should list the control points of a third-order Bézier curve.

count-from (integer)

The first measure in a measure count receives this number. The following measures are numbered in increments from this initial value.

damping (number)

Amount of beam slope damping.

dash-definition (pair)

List of dash-elements defining the dash structure. Each dash-element has a starting t value, an ending t-value, a dash-fraction, and a dash-period.

dash-fraction (number)

Size of the dashes, relative to dash-period. Should be between 0.1 and 1.0 (continuous line). If set to 0.0, a dotted line is produced

dash-period (number)

The length of one dash together with whitespace. If negative, no line is drawn at all.

dashed-edge (boolean)

If set, the bracket edges are dashed like the rest of the bracket.

default-direction (direction)

Direction determined by note head positions.

default-staff-staff-spacing (list)

The settings to use for staff-staff-spacing when it is unset, for ungrouped staves and for grouped staves that do not have the relevant StaffGrouper property set (staff-staff-spacing or staffgroup-staff-spacing).

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.

digit-names (vector)

Names for string finger digits.

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.

dot-count (integer)

The number of dots.

dot-negative-kern (number)

The space to remove between a dot and a slash in percent repeat glyphs. Larger values bring the two elements closer together.

dot-placement-list (list)

List consisting of (description string-number fret-number finger-number) entries used to define fret diagrams.

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.

eccentricity (number)

How asymmetrical to make a slur. Positive means move the center to the right.

edge-height (pair)

A pair of numbers specifying the heights of the vertical edges: (left-height . right-height).

edge-text (pair)

A pair specifying the texts to be set at the edges: (left-text . right-text).

endpoint-alignments (pair of numbers)

A pair of numbers representing the alignments of an object’s endpoints. E.g., the ends of a hairpin relative to NoteColumn grobs.

expand-limit (integer)

Maximum number of measures expanded in church rests.

extra-dy (number)

Slope glissandi this much extra.

extra-offset (pair of numbers)

A pair representing an offset. This offset is added just before outputting the symbol, so the typesetting engine is completely oblivious to it. The values are measured in staff-space units of the staff’s StaffSymbol.

extra-spacing-height (pair of numbers)

In the horizontal spacing problem, we increase the height of each item by this amount (by adding the ‘car’ to the bottom of the item and adding the ‘cdr’ to the top of the item). In order to make a grob infinitely high (to prevent the horizontal spacing problem from placing any other grobs above or below this grob), set this to (-inf.0 . +inf.0).

extra-spacing-width (pair of numbers)

In the horizontal spacing problem, we pad each item by this amount (by adding the ‘car’ on the left side of the item and adding the ‘cdr’ on the right side of the item). In order to make a grob take up no horizontal space at all, set this to (+inf.0 . -inf.0).

extroversion (number)

For polygons, how the thickness of the line is spread on each side of the exact polygon whith ideal zero thickness. If this is 0, the middle of line is on the polygon. If 1, the line sticks out of the polygon. If -1, the outer side of the line is exactly on the polygon. Other numeric values are interpolated.

fa-merge-direction (direction)

If two ‘fa’ shape note heads get merged that are both listed in the fa-styles property but have different stem directions, enforce this note head direction for display.

filled (boolean)

Whether an object is filled with ink.

flag-count (number)

The number of tremolo beams.

flag-style (symbol)

The style of the flag to be used with MetronomeMark. Available are 'modern-straight-flag, 'old-straight-flag, 'flat-flag, 'mensural, 'stacked, and 'default.

flat-positions (list)

Flats in key signatures are placed within the specified ranges of staff positions. The general form is a list of pairs, with one pair for each type of clef, in order of the staff position at which each clef places C: (alto treble tenor soprano baritone mezzosoprano bass). If the list contains a single element it applies for all clefs. A single number in place of a pair sets accidentals within the octave ending at that staff position.

font-encoding (symbol)

The font encoding is the broadest category for selecting a font. Currently, only lilypond’s system fonts (Emmentaler) are using this property. Available values are fetaMusic (Emmentaler), fetaBraces, fetaText (Emmentaler).

font-family (symbol)

The font family is the broadest category for selecting text fonts. Options include serif, sans and typewriter.

font-features (list)

Opentype features.

font-name (string)

This property is kept for backwards compatibility only. Use the fonts property instead.

font-series (symbol)

Select the series of a font. Common choices are normal and bold. The full list of symbols that can be used is: thin, ultralight, light, semilight, book, normal, medium, semibold, bold, ultrabold, heavy, ultraheavy.

font-shape (symbol)

Select the shape of a font. Possible values are upright, italic, oblique, and slanted (which is the same as oblique).

font-size (number)

The font size, compared to the ‘normal’ size. 0 is style-sheet’s normal size, -1 is smaller, +1 is bigger. Each step of 1 is approximately 12% larger; 6 steps are exactly a factor 2 larger. If the context property fontSize is set, its value is added to this before the glyph is printed. Fractional values are allowed.

font-stretch (symbol)

Select a condensed or expanded font, if available in the font family. Possible values are ultra-condensed, extra-condensed, condensed, semi-condensed, normal, semi-expanded, expanded, extra-expanded, and ultra-expanded.

font-variant (symbol)

Select the variant of a font. Choices include normal and small-caps.

fonts (alist, with symbols as keys)

An alist mapping font families to font names. The standard font families are music, serif, sans and typewriter.

footnote (boolean)

Should this be a footnote or in-note?

footnote-music (music)

Music creating a footnote.

footnote-text (markup)

A footnote for the grob.

force-hshift (number)

This specifies a manual shift for notes in collisions. The unit is the note head width of the first down-stem voice note; if there are no down-stem voices, the width of the first up-stem voice note is taken instead. This is used by note-collision-interface.

forced-spacing (number)

Spacing forced between grobs, used in various ligature engravers.

fraction (fraction, as pair)

Numerator and denominator of a time signature object.

french-beaming (boolean)

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

fret-diagram-details (alist, with symbols as keys)

An alist of detailed grob properties for fret diagrams. Each alist entry consists of a (property . value) pair. The properties which can be included in fret-diagram-details include the following:

  • barre-type – Type of barre indication used. Choices include curved, straight, and none. Default curved.
  • capo-thickness – Thickness of capo indicator, in multiples of fret-space. Default value 0.5.
  • dot-color – Color of dots. Options include black and white. Default black.
  • dot-label-font-mag – Magnification for font used to label fret dots. Default value 1.
  • dot-position – Location of dot in fret space. Default 0.6 for dots without labels, 0.95-dot-radius for dots with labels.
  • dot-radius – Radius of dots, in terms of fret spaces. Default value 0.425 for labeled dots, 0.25 for unlabeled dots.
  • finger-code – Code for the type of fingering indication used. Options include none, in-dot, and below-string. Default none for markup fret diagrams, below-string for FretBoards fret diagrams.
  • fret-count – The number of frets. Default 4.
  • fret-distance – Multiplier to adjust the distance between frets. Default 1.0.
  • fret-label-custom-format – The format string to be used label the lowest fret number, when number-type equals to custom. Default "~a".
  • fret-label-font-mag – The magnification of the font used to label the lowest fret number. Default 0.5.
  • fret-label-vertical-offset – The offset of the fret label from the center of the fret in direction parallel to strings. Default 0.
  • fret-label-horizontal-offset – The offset of the fret label from the center of the fret in direction orthogonal to strings. Default 0.
  • handedness – Print the fret-diagram left- or right-handed. -1, LEFT for left ; 1, RIGHT for right. Default RIGHT.
  • paren-padding – The padding for the parenthesis. Default 0.05.
  • label-dir – Side to which the fret label is attached. -1, LEFT, or DOWN for left or down; 1, RIGHT, or UP for right or up. Default RIGHT.
  • mute-string – Character string to be used to indicate muted string. Default "x".
  • number-type – Type of numbers to use in fret label. Choices include arabic, roman-ij-lower, roman-ij-upper, roman-lower, roman-upper, arabic and custom. In the last case, the format string is supplied by the fret-label-custom-format property. Default roman-lower.
  • open-string – Character string to be used to indicate open string. Default "o".
  • orientation – Orientation of fret-diagram. Options include normal, landscape, and opposing-landscape. Default normal.
  • string-count – The number of strings. Default 6.
  • string-distance – Multiplier to adjust the distance between strings. Default 1.0.
  • string-label-font-mag – The magnification of the font used to label fingerings at the string, rather than in the dot. Default value 0.6 for normal orientation, 0.5 for landscape and opposing-landscape.
  • string-thickness-factor – Factor for changing thickness of each string in the fret diagram. Thickness of string k is given by thickness * (1+string-thickness-factor) ^ (k-1). Default 0.
  • top-fret-thickness – The thickness of the top fret line, as a multiple of the standard thickness. Default value 3.
  • xo-font-magnification – Magnification used for mute and open string indicators. Default value 0.5.
  • xo-padding – Padding for open and mute indicators from top fret. Default value 0.25.
full-length-padding (number)

How much padding to use at the right side of a full-length tuplet bracket.

full-length-to-extent (boolean)

Run to the extent of the column for a full-length tuplet bracket.

full-measure-extra-space (number)

Extra space that is allocated at the beginning of a measure with only one note. This property is read from the NonMusicalPaperColumn that begins the measure.

full-size-change (boolean)

Don’t make a change clef smaller.

gap (dimension, in staff space)

Size of a gap in a variable symbol.

gap-count (integer)

Number of gapped beams for tremolo.

glissando-skip (boolean)

Should this NoteHead be skipped by glissandi?

glyph (string)

A string determining what ‘style’ of glyph is typeset. Valid choices depend on the function that is reading this property.

In combination with (span) bar lines, it is a string resembling the bar line appearance in ASCII form.

glyph-left (string)

The glyph value to use at the end of the line when the line is broken. #f indicates that no glyph should be visible; otherwise the value must be a string.

glyph-name (string)

The glyph name within the font.

In the context of (span) bar lines or clefs, glyph-name represents a processed form of glyph, where decisions about line breaking, etc., are already taken.

glyph-right (string)

The glyph value to use at the beginning of the line when the line is broken. #f indicates that no glyph should be visible; otherwise the value must be a string.

graphical (boolean)

Display in graphical (vs. text) form.

grow-direction (direction)

Crescendo or decrescendo?

hair-thickness (number)

Thickness of the thin line in a bar line, expressed as a multiple of the default staff-line thickness (i.e., the visual output is not influenced by changes to Staff.StaffSymbol.thickness).

harp-pedal-details (alist, with symbols as keys)

An alist of detailed grob properties for harp pedal diagrams. Each alist entry consists of a (property . value) pair. The properties which can be included in harp-pedal-details include the following:

  • box-offset – Vertical shift of the center of flat/sharp pedal boxes above/below the horizontal line. Default value 0.8.
  • box-width – Width of each pedal box. Default value 0.4.
  • box-height – Height of each pedal box. Default value 1.0.
  • space-before-divider – Space between boxes before the first divider (so that the diagram can be made symmetric). Default value 0.8.
  • space-after-divider – Space between boxes after the first divider. Default value 0.8.
  • circle-thickness – Thickness (in unit of the line-thickness) of the ellipse around circled pedals. Default value 0.5.
  • circle-x-padding – Padding in X direction of the ellipse around circled pedals. Default value 0.15.
  • circle-y-padding – Padding in Y direction of the ellipse around circled pedals. Default value 0.2.
head-direction (direction)

Are the note heads left or right in a semitie?

height (dimension, in staff space)

Height of an object in staff-space units.

height-limit (dimension, in staff space)

Maximum slur height: The longer the slur, the closer it is to this height.

hide-tied-accidental-after-break (boolean)

If set, an accidental that appears on a tied note after a line break will not be displayed.

horizon-padding (number)

The amount to pad the axis along which a Skyline is built for the side-position-interface.

horizontal-shift (integer)

An integer that identifies ranking of NoteColumns for horizontal shifting. This is used by note-collision-interface.

horizontal-skylines (pair of skylines)

Two skylines, one to the left and one to the right of this grob.

id (string)

An id string for the grob.

ignore-ambitus (boolean)

If set, don’t consider this notehead for ambitus calculation.

ignore-collision (boolean)

If set, don’t do note collision resolution on this NoteColumn.

implicit (boolean)

Is this an implicit bass figure?

inspect-quants (pair of numbers)

If debugging is set, set beam and slur position to a (quantized) position that is as close as possible to this value, and print the demerits for the inspected position in the output.

keep-inside-line (boolean)

If set, this column cannot have objects sticking into the margin.

kern (dimension, in staff space)

The space between individual elements in any compound bar line, expressed as a multiple of the default staff-line thickness (i.e., the visual output is not influenced by changes to Staff.StaffSymbol.thickness).

knee (boolean)

Is this beam kneed?

knee-spacing-correction (number)

Factor for the optical correction amount for kneed beams. Set between 0 for no correction and 1 for full correction.

knee-to-beam (boolean)

Determines whether a tuplet number will be positioned next to a kneed beam.

labels (list)

List of labels (symbols) placed on a column.

layer (integer)

An integer which determines the order of printing objects. Objects with the lowest value of layer are drawn first, then objects with progressively higher values are drawn, so objects with higher values overwrite objects with lower values. By default most objects are assigned a layer value of 1.

ledger-extra (dimension, in staff space)

Extra distance from staff line to draw ledger lines for.

ledger-line-thickness (pair of numbers)

The thickness of ledger lines. It is the sum of 2 numbers: The first is the factor for line thickness, and the second for staff space. Both contributions are added.

ledger-positions (list)

Vertical positions of ledger lines. When set on a StaffSymbol grob it defines a repeating pattern of ledger lines and any parenthesized groups will always be shown together.

ledger-positions-function (any type)

A quoted Scheme procedure that takes a StaffSymbol grob and the vertical position of a note head as arguments and returns a list of ledger line positions.

left-bound-info (alist, with symbols as keys)

An alist of properties for determining attachments of spanners to edges.

left-number-text (markup)

For a measure counter, this is the formatted measure count. When the measure counter extends over several measures (like with compressed multi-measure rests), it is the text on the left side of the dash.

left-padding (dimension, in staff space)

The amount of space that is put left to an object (e.g., a lyric extender).

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.

line-break-penalty (number)

Penalty for a line break at this column. This affects the choices of the line breaker; it avoids a line break at a column with a positive penalty and prefers a line break at a column with a negative penalty.

line-break-permission (symbol)

Instructs the line breaker on whether to put a line break at this column. Can be force or allow.

line-break-system-details (alist, with symbols as keys)

An alist of properties to use if this column is the start of a system.

line-count (integer)

The number of staff lines.

line-positions (list)

Vertical positions of staff lines.

line-thickness (number)

For slurs and ties, this is the diameter of the virtual “pen” that draws the two arcs of the curve’s outline, which intersect at the endpoints. 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).

long-text (markup)

Text markup. See Formatting text.

main-extent (pair of numbers)

The horizontal extent of a NoteColumn grob without taking suspended NoteHead grobs into account (i.e., NoteHeads forced into the unnatural direction of the Stem because of a chromatic clash).

max-beam-connect (integer)

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

max-slope-factor (non-negative number)

Factor for calculating the maximum tuplet bracket slope. Notice that there exists a homonymous property for slurs.

max-symbol-separation (number)

The maximum distance between symbols making up a church rest.

maximum-gap (number)

Maximum value allowed for gap property.

measure-count (integer)

The number of measures for a multi-measure rest.

measure-division (number list)

A list representing what fraction of the measure length each chord name takes in a chord square. The list is made of exact numbers between 0 and 1, which should add up to 1. Example: a measure c2 g4 g4 results in '(1/2 1/4 1/4).

measure-division-chord-placement-alist (association list (list of pairs))

An alist mapping measure divisions (see the measure-division property) to lists of coordinates (number pairs) applied to the chord names of a chord square. Coordinates are normalized between -1 and 1 within the square.

measure-division-lines-alist (association list (list of pairs))

An alist mapping measure divisions (see the measure-division property) to lists of lines to draw in the square, given as 4-element lists: (x-start y-start x-end y-end).

measure-length (positive moment with no grace part)

Length of a measure. Used in some spacing situations.

merge-differently-dotted (boolean)

Merge note heads in collisions, even if they have a different number of dots. This is normal notation for some types of polyphonic music.

merge-differently-dotted only applies to opposing stem directions (i.e., voice 1 & 2).

merge-differently-headed (boolean)

Merge note heads in collisions, even if they have different note heads. The smaller of the two heads is rendered invisible. This is used in polyphonic guitar notation. The value of this setting is used by note-collision-interface.

merge-differently-headed only applies to opposing stem directions (i.e., voice 1 & 2).

minimum-distance (dimension, in staff space)

Minimum distance between rest and notes or beam.

minimum-length (dimension, in staff space)

Try to make a spanner at least this long, normally in the horizontal direction. This requires an appropriate callback for the springs-and-rods property. If added to a Tie, this sets the minimum distance between noteheads.

minimum-length-after-break (dimension, in staff space)

If set, try to make a broken spanner starting a line this long. This requires an appropriate callback for the springs-and-rods property. If added to a Tie, this sets the minimum distance to the notehead.

minimum-length-fraction (number)

Minimum length of ledger line as fraction of note head size.

minimum-space (dimension, in staff space)

Minimum distance that the victim should move (after padding).

minimum-X-extent (pair of numbers)

Minimum size of an object in X dimension, measured in staff-space units.

minimum-X-space (dimension, in staff space)

Minimum distance that the victim should move horizontally (after padding), overriding the minimum-space property value.

minimum-Y-extent (pair of numbers)

Minimum size of an object in Y dimension, measured in staff-space units.

musical-length (non-negative moment with no grace part)

Musical length.

neutral-direction (direction)

Which direction to take in the center of the staff.

neutral-position (number)

Position (in half staff spaces) where to flip the direction of custos stem.

next (graphical (layout) object)

Object that is next relation (e.g., the lyric syllable following an extender).

no-ledgers (boolean)

If set, don’t draw ledger lines on this object.

no-stem-extend (boolean)

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

non-break-align-symbols (list)

A list of symbols that determine which NON-break-aligned interfaces to align this to.

non-default (boolean)

Set for manually specified clefs and keys.

non-musical (boolean)

True if the grob belongs to a NonMusicalPaperColumn.

nonstaff-nonstaff-spacing (alist, with symbols as keys)

The spacing alist controlling the distance between the current non-staff line and the next non-staff line in the direction of staff-affinity, if both are on the same side of the related staff, and staff-affinity is either UP or DOWN. See staff-staff-spacing for a description of the alist structure.

nonstaff-relatedstaff-spacing (alist, with symbols as keys)

The spacing alist controlling the distance between the current non-staff line and the nearest staff in the direction of staff-affinity, if there are no non-staff lines between the two, and staff-affinity is either UP or DOWN. If staff-affinity is CENTER, then nonstaff-relatedstaff-spacing is used for the nearest staves on both sides, even if other non-staff lines appear between the current one and either of the staves. See staff-staff-spacing for a description of the alist structure.

nonstaff-unrelatedstaff-spacing (alist, with symbols as keys)

The spacing alist controlling the distance between the current non-staff line and the nearest staff in the opposite direction from staff-affinity, if there are no other non-staff lines between the two, and staff-affinity is either UP or DOWN. See staff-staff-spacing for a description of the alist structure.

normalized-endpoints (pair)

Represents left and right placement over the total spanner, where the width of the spanner is normalized between 0 and 1.

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.

note-names (vector)

Vector of strings containing names for easy-notation note heads.

number-range-separator (markup)

For a measure counter extending over several measures (like with compressed multi-measure rests), this is the separator between the two printed numbers.

number-type (symbol)

Numbering style. Choices include arabic, roman-ij-lower, roman-ij-upper, roman-lower, and roman-upper.

output-attributes (association list (list of pairs))

An alist of attributes for the grob, to be included in output files. When the SVG typesetting backend is used, the attributes are assigned to a group (<g>) containing all of the stencils that comprise a given grob. For example,

'((id . 123) (class . foo) (data-whatever . "bar"))

produces

<g id="123" class="foo" data-whatever="bar"> … </g>

In the Postscript backend, where there is no way to group items, the setting of the output-attributes property has no effect.

outside-staff-horizontal-padding (number)

By default, an outside-staff-object can be placed so that is it very close to another grob horizontally. If this property is set, the outside-staff-object is raised so that it is not so close to its neighbor.

outside-staff-padding (number)

The padding to place between grobs when spacing according to outside-staff-priority. Two grobs with different outside-staff-padding values have the larger value of padding between them.

outside-staff-placement-directive (symbol)

One of four directives telling how outside staff objects should be placed.

  • left-to-right-greedy – Place each successive grob from left to right.
  • left-to-right-polite – Place a grob from left to right only if it does not potentially overlap with another grob that has been placed on a pass through a grob array. If there is overlap, do another pass to determine placement.
  • right-to-left-greedy – Same as left-to-right-greedy, but from right to left.
  • right-to-left-polite – Same as left-to-right-polite, but from right to left.
outside-staff-priority (number)

If set, the grob is positioned outside the staff in such a way as to avoid all collisions. In case of a potential collision, the grob with the smaller outside-staff-priority is closer to the staff.

packed-spacing (boolean)

If set, the notes are spaced as tightly as possible.

padding (dimension, in staff space)

Add this much extra space between objects that are next to each other.

padding-pairs (association list (list of pairs))

An alist of padding pairs for key signatures (and key cancellations). Each alist entry has the form

((left-glyph-name . right-glyph-name) . dist)

specifying the padding dist between two adjacent key signature elements. If there is no entry in the alist for a given pair, the padding value given by the padding property of the KeySignature (or KeyCancellation) grob is used instead.

A special feature is the handling of adjacent naturals (to be more precise, the handling of glyph accidentals.natural): If there is no ‘natural-natural’ entry in padding-pairs explicitly overriding it, LilyPond adds some extra padding (in addition to the grob’s padding value) to avoid collisions.

page-break-penalty (number)

Penalty for page break at this column. This affects the choices of the page breaker; it avoids a page break at a column with a positive penalty and prefers a page break at a column with a negative penalty.

page-break-permission (symbol)

Instructs the page breaker on whether to put a page break at this column. Can be force or allow.

page-number (number)

Page number on which this system ends up.

page-turn-penalty (number)

Penalty for a page turn at this column. This affects the choices of the page breaker; it avoids a page turn at a column with a positive penalty and prefers a page turn at a column with a negative penalty.

page-turn-permission (symbol)

Instructs the page breaker on whether to put a page turn at this column. Can be force or allow.

parent-alignment-X (number)

Specify on which point of the parent the object is aligned. The value -1 means aligned on parent’s left edge, 0 on center, and 1 right edge, in X direction. Other numerical values may also be specified - the unit is half the parent’s width. If not a number, align on the parent’s reference point. If unset, the value from self-alignment-X property will be used.

parent-alignment-Y (number)

Like parent-alignment-X but for the Y axis.

parenthesis-friends (list)

A list of Grob types, as symbols. When parentheses enclose a Grob that has ’parenthesis-friends, the parentheses widen to include any child Grobs with type among ’parenthesis-friends.

parenthesis-id (symbol)

When parenthesized grobs created in the same time step have this property, there is one set of parentheses for each group of grobs having the same value.

parenthesized (boolean)

Parenthesize this grob.

positions (pair of numbers)

Pair of staff coordinates (start . end), where start and end are vertical positions in staff-space units of the current staff. For slurs, this value selects which slur candidate to use; if extreme positions are requested, the closest one is taken.

prefer-dotted-right (boolean)

For note collisions, prefer to shift dotted up-note to the right, rather than shifting just the dot.

protrusion (number)

In an arpeggio bracket, the length of the horizontal edges.

range-collapse-threshold (non-negative, exact integer)

If the length of a volta range is greater than or equal to this threshold, print it with a dash. For example, if this is 3, a \volta 1,2,3 is printed as ‘1.-3.’, but if it is 4, it is printed as ‘1.2.3.’.

rank-on-page (number)

0-based index of the system on a page.

ratio (number)

Parameter for slur shape. The higher this number, the quicker the slur attains its height-limit.

remove-empty (boolean)

If set, remove group if it contains no interesting items.

remove-first (boolean)

Remove the first staff of an orchestral score?

remove-layer (index or symbol)

When set as a positive integer, the Keep_alive_together_engraver removes all VerticalAxisGroup grobs with a remove-layer larger than the smallest retained remove-layer. Set to #f to make a layer independent of the Keep_alive_together_engraver. Set to '(), the layer does not participate in the layering decisions. The property can also be set as a symbol for common behaviors: #'any to keep the layer alive with any other layer in the group; #'above or #'below to keep the layer alive with the context immediately before or after it, respectively.

replacement-alist (association list (list of pairs))

Alist of strings. The key is a string of the pattern to be replaced. The value is a string of what should be displayed. Useful for ligatures.

restore-first (boolean)

Print a natural before the accidental.

rhythmic-location (rhythmic location)

Where (bar number, measure position) in the score.

right-bound-info (alist, with symbols as keys)

An alist of properties for determining attachments of spanners to edges.

right-justified (boolean)

Used for BarLines to right-align them. Usually the extent of a BarLine has some positive value to the right. If this property is set to #t, BarLine.stencil is translated to the left by this value. Needs to be set at Score or StaffGroup level. As a result all BarLines of said Score or StaffGroup are right-justified.

right-number-text (markup)

When the measure counter extends over several measures (like with compressed multi-measure rests), this is the text on the right side of the dash. Usually unset.

right-padding (dimension, in staff space)

Space to insert on the right side of an object (e.g., between note and its accidentals).

rotation (list)

Number of degrees to rotate this object, and what point to rotate around. For example, '(45 0 0) rotates by 45 degrees around the center of this object.

round-up-exceptions (list)

A list of pairs where car is the numerator and cdr the denominator of a moment. Each pair in this list means that the multi-measure rests of the corresponding length will be rounded up to the longer rest. See round-up-to-longer-rest.

round-up-to-longer-rest (boolean)

Displays the longer multi-measure rest when the length of a measure is between two values of usable-duration-logs. For example, displays a breve instead of a whole in a 3/2 measure.

rounded (boolean)

Decide whether lines should be drawn rounded or not.

same-direction-correction (number)

Optical correction amount for stems that are placed in tight configurations. This amount is used for stems with the same direction to compensate for note head to stem distance.

script-priority (number)

A key for determining the order of scripts in a stack, by being added to the position of the script in the user input, the sum being the overall priority. Smaller means closer to the head.

segno-kern (number)

The space between the two thin lines of the segno bar line symbol, expressed as a multiple of the default staff-line thickness (i.e., the visual output is not influenced by changes to Staff.StaffSymbol.thickness).

self-alignment-X (number)

Specify alignment of an object. The value -1 means left aligned, 0 centered, and 1 right-aligned in X direction. Other numerical values may also be specified - the unit is half the object width. If not a number, align on the object’s reference point.

self-alignment-Y (number)

Like self-alignment-X but for the Y axis.

senza-misura-stencil (stencil)

The symbol to print when TimeSignature.fraction is not set. Overriding TimeSignature.stencil circumvents this.

shape (symbol)

This setting determines what shape a grob has. Valid choices depend on the stencil callback reading this property.

sharp-positions (list)

Sharps in key signatures are placed within the specified ranges of staff positions. The general form is a list of pairs, with one pair for each type of clef, in order of the staff position at which each clef places C: (alto treble tenor soprano baritone mezzosoprano bass). If the list contains a single element it applies for all clefs. A single number in place of a pair sets accidentals within the octave ending at that staff position.

short-bar-extent (pair of numbers)

The Y-extent of a short bar line. The default is half the normal bar extent, rounded up to an integer number of staff spaces.

shorten-pair (pair of numbers)

The lengths to shorten on both sides a hairpin or text-spanner such as a pedal bracket. Positive values shorten the hairpin or text-spanner, while negative values lengthen it.

shortest-duration-space (number)

Start with this multiple of spacing-increment space for the shortest duration. See also spacing-spanner-interface.

shortest-playing-duration (moment)

The duration of the shortest note playing here.

shortest-starter-duration (moment)

The duration of the shortest note that starts here.

show-control-points (boolean)

For grobs printing Bézier curves, setting this property to #t causes the control points and control polygon to be drawn on the page for ease of tweaking.

show-horizontal-skylines (boolean)

If true, print this grob’s horizontal skylines. This is meant for debugging purposes.

show-vertical-skylines (boolean)

If true, print this grob’s vertical skylines. This is meant for debugging purposes.

side-axis (number)

If the value is X (or equivalently 0), the object is placed horizontally next to the other object. If the value is Y or 1, it is placed vertically.

side-relative-direction (direction)

Multiply direction of direction-source with this to get the direction of this object.

size (number)

The ratio of the size of the object to its default size.

skip-quanting (boolean)

Should beam quanting be skipped?

skyline-horizontal-padding (number)

For determining the vertical distance between two staves, it is possible to have a configuration which would result in a tight interleaving of grobs from the top staff and the bottom staff. The larger this parameter is, the farther apart the staves are placed in such a configuration.

skyline-vertical-padding (number)

The amount by which the left and right skylines of a column are padded vertically, beyond the Y-extents and extra-spacing-heights of the constituent grobs in the column. Increase this to prevent interleaving of grobs from adjacent columns.

slash-negative-kern (number)

The space to remove between slashes in percent repeat glyphs. Larger values bring the two elements closer together.

slope (number)

The slope of this object.

slur-padding (number)

Extra distance between slur and script.

snap-radius (number)

The maximum distance between two objects that will cause them to snap to alignment along an axis.

space-alist (alist, with symbols as keys)

An alist that specifies distances from this grob to other breakable items, using the format:

'((break-align-symbol . (spacing-style . space))
  (break-align-symbol . (spacing-style . space))
  ...)

Standard choices for break-align-symbol are listed in break-alignment-interface. Additionally, three special break-align symbols available to space-alist are:

first-note

used when the grob is just left of the first note on a line

next-note

used when the grob is just left of any other note; if not set, the value of first-note gets used

right-edge

used when the grob is the last item on the line (only compatible with the extra-space spacing style)

If space-alist is defined for a grob that gets spaced in a staff, an entry for first-note must be present. If there is no next-note entry, the value of first-note is used instead.

Choices for spacing-style are:

extra-space

Put this much space between the two grobs. The space is stretchable and shrinkable when paired with first-note or next-note; otherwise it is fixed.

minimum-space

Put at least this much space between the left sides of both grobs, without allowing them to collide. The space is stretchable and shrinkable when paired with first-note or next-note; otherwise it is fixed. Not compatible with right-edge.

fixed-space

Only compatible with first-note and next-note. Put this much fixed space between the grob and the note.

minimum-fixed-space

Only compatible with first-note and next-note. Put at least this much fixed space between the left side of the grob and the left side of the note, without allowing them to collide.

semi-fixed-space

Only compatible with first-note and next-note. Put this much space between the grob and the note, such that half of the space is fixed and half is stretchable and shrinkable.

shrink-space

Only compatible with first-note and next-note. Put this much space between the two grobs. The space is only shrinkable.

semi-shrink-space

Only compatible with first-note and next-note. Put this much space between the grob and the note, such that half of the space is fixed and half is shrinkable.

Rules for this spacing are much more complicated than this. See [Wanske] page 126–134, [Ross] page 143–147.

space-to-barline (boolean)

If set, the distance between a note and the following non-musical column will be measured to the bar line instead of to the beginning of the non-musical column. If there is a clef change followed by a bar line, for example, this means that we will try to space the non-musical column as though the clef is not there.

spacing-increment (dimension, in staff space)

The unit of length for note-spacing. Typically, the width of a note head. See also spacing-spanner-interface.

spacing-pair (pair)

A pair of alignment symbols which set an object’s spacing relative to its left and right BreakAlignments.

For example, a MultiMeasureRest will ignore prefatory items at its bounds (i.e., clefs, key signatures and time signatures) using the following override:

\override MultiMeasureRest.spacing-pair =
             #'(staff-bar . staff-bar)
span-all-note-heads (boolean)

If true, tuplet brackets are printed spanning horizontally from the first to the last note head instead of covering only the stems.

spanner-id (index or symbol)

An identifier to distinguish concurrent spanners.

springs-and-rods (boolean)

Dummy variable for triggering spacing routines.

stacking-dir (direction)

Stack objects in which direction?

staff-affinity (direction)

The direction of the staff to use for spacing the current non-staff line. Choices are UP, DOWN, and CENTER. If CENTER, the non-staff line will be placed equidistant between the two nearest staves on either side, unless collisions or other spacing constraints prevent this. Setting staff-affinity for a staff causes it to be treated as a non-staff line. Setting staff-affinity to #f causes a non-staff line to be treated as a staff.

staff-padding (dimension, in staff space)

Maintain this much space between reference points and the staff. Its effect is to align objects of differing sizes (like the dynamics p and f) on their baselines.

staff-position (number)

Vertical position, measured in half staff spaces, counted from the middle line.

For ties, there is a distinction between exact and inexact values: an exact value serves as a rough vertical offset that gets further tuned to make the tie avoid staff lines. An inexact value is taken as the precise vertical offset without further adjustments.

staff-space (dimension, in staff space)

Amount of space between staff lines, expressed in global staff-space.

staff-staff-spacing (alist, with symbols as keys)

When applied to a staff-group’s StaffGrouper grob, this spacing alist controls the distance between consecutive staves within the staff-group. When applied to a staff’s VerticalAxisGroup grob, it controls the distance between the staff and the nearest staff below it in the same system, replacing any settings inherited from the StaffGrouper grob of the containing staff-group, if there is one. This property remains in effect even when non-staff lines appear between staves. The alist can contain the following keys:

  • basic-distance – the vertical distance, measured in staff-spaces, between the reference points of the two items when no collisions would result, and no stretching or compressing is in effect.
  • minimum-distance – the smallest allowable vertical distance, measured in staff-spaces, between the reference points of the two items, when compressing is in effect.
  • padding – the minimum required amount of unobstructed vertical whitespace between the bounding boxes (or skylines) of the two items, measured in staff-spaces.
  • stretchability – a unitless measure of the dimension’s relative propensity to stretch. If zero, the distance will not stretch (unless collisions would result).
staffgroup-staff-spacing (alist, with symbols as keys)

The spacing alist controlling the distance between the last staff of the current staff-group and the staff just below it in the same system, even if one or more non-staff lines exist between the two staves. If the staff-staff-spacing property of the staff’s VerticalAxisGroup grob is set, that is used instead. See staff-staff-spacing for a description of the alist structure.

stem-attachment (pair of numbers)

An (x . y) pair where the stem attaches to the notehead.

stem-begin-position (number)

User override for the begin position of a stem.

stem-spacing-correction (number)

Optical correction amount for stems that are placed in tight configurations. For opposite directions, this amount is the correction for two normal sized stems that overlap completely.

stemlet-length (number)

How long should be a stem over a rest?

stencil (stencil)

The symbol to print.

stencils (list)

Multiple stencils, used as intermediate value.

strict-grace-spacing (boolean)

If set, main notes are spaced normally, then grace notes are put left of the musical columns for the main notes.

strict-note-spacing (boolean)

If set, unbroken columns with non-musical material (clefs, bar lines, etc.) are not spaced separately, but put before musical columns.

stroke-style (string)

Set to "grace" to turn stroke through flag on.

style (symbol)

This setting determines in what style a grob is typeset. Valid choices depend on the stencil callback reading this property.

text (markup)

Text markup. See Formatting text.

text-alignment-X (number)

How to align an annotation horizontally.

text-alignment-Y (number)

How to align an annotation vertically.

text-direction (direction)

This controls the ordering of the words. The default RIGHT is for roman text. Arabic or Hebrew should use LEFT.

thick-thickness (number)

Thickness of the thick line in a bar line, expressed as a multiple of the default staff-line thickness (i.e., the visual output is not influenced by changes to Staff.StaffSymbol.thickness).

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).

tie-configuration (list)

List of (position . dir) pairs, indicating a desired tie configuration that overrides the default. position is the offset from the center of the staff in half staff-space units, and dir indicates the direction of the tie (1=>up, -1=>down, 0=>center). A non-pair entry in the list causes the corresponding tie to be formatted automatically.

There is a distinction between exact and inexact values for position: an exact value serves as a rough vertical offset that gets further tuned to make the tie avoid staff lines. An inexact value is taken as the precise vertical offset without further adjustments.

to-barline (boolean)

If true, the spanner will stop at the bar line just before it would otherwise stop.

toward-stem-shift (number)

Amount by which scripts are shifted toward the stem if their direction coincides with the stem direction. 0.0 means centered on the note head (the default position of most scripts); 1.0 means centered on the stem. Interpolated values are possible.

toward-stem-shift-in-column (number)

Amount by which a script is shifted toward the stem if its direction coincides with the stem direction and it is associated with a ScriptColumn object. 0.0 means centered on the note head (the default position of most scripts); 1.0 means centered on the stem. Interpolated values are possible.

transparent (boolean)

This makes the grob invisible.

tuplet-slur (boolean)

Draw a slur instead of a bracket for tuplets.

uniform-stretching (boolean)

If set, items stretch proportionally to their natural separation based on durations. This looks better in complex polyphonic patterns.

usable-duration-logs (list)

List of duration-logs that can be used in typesetting the grob.

used (boolean)

If set, this spacing column is kept in the spacing problem.

vertical-skylines (pair of skylines)

Two skylines, one above and one below this grob.

visible-over-note-heads (boolean)

This prints a tuplet bracket when the bracket is set to be over the note heads. This option can be combined with the default tuplet bracket visibility style and with #'if-no-beam.

voiced-position (number)

The staff position of a voiced Rest, negative if the rest has direction DOWN.

volta-number-offset (pair of numbers)

The offset of the volta number relative to the upper left corner of the volta bracket.

when (moment)

Global time step associated with this column.

whiteout (boolean-or-number)

If a number or true, the grob is printed over a white background to white-out underlying material, if the grob is visible. A number indicates how far the white background extends beyond the bounding box of the grob as a multiple of the staff-line thickness. The LyricHyphen grob uses a special implementation of whiteout: A positive number indicates how far the white background extends beyond the bounding box in multiples of line-thickness. The shape of the background is determined by whiteout-style. Usually #f by default.

whiteout-style (symbol)

Determines the shape of the whiteout background. Available are 'outline, 'rounded-box, and the default 'box. There is one exception: Use 'special for LyricHyphen.

widened-extent (pair of numbers)

The vertical extent that a bar line on a certain staff symbol should have. If the staff symbol is small (e.g., has just one line, as in a RhythmicStaff, this is wider than the staff symbol’s Y extent.

width (dimension, in staff space)

The width of a grob measured in staff space.

woodwind-diagram-details (alist, with symbols as keys)

An alist of detailed grob properties for woodwind diagrams. Each alist entry consists of a (property . value) pair. The properties which can be included in woodwind-diagram-details include the following:

  • fill-angle – Rotation angle of a partially filled key from horizontal. Default value 0.
  • text-trill-circled – In non-graphical mode, for keys shown as text, indicate a trill by circling the text if true, or by shading the text if false. Default value #t.
word-space (dimension, in staff space)

Space to insert between words in texts.

X-align-on-main-noteheads (boolean)

If true, this grob will ignore suspended noteheads when aligning itself on NoteColumn.

X-alignment-extent (pair of numbers)

If a grob wants to align itself on a PaperColumn grob that doesn’t contain note heads, use this horizontal extent as a placeholder.

X-attachment (number)

Horizontal attachment of a line on a frame, typically between -1 (left) and 1 (right).

X-extent (pair of numbers)

Extent (size) in the X direction, measured in staff-space units, relative to object’s reference point.

X-offset (number)

The horizontal amount that this object is moved relative to its X-parent.

Note that many objects have special positioning considerations, which cause any setting of X-offset to be ignored or modified, even though the object supports the self-alignment-interface.

X-padding (dimension, in staff space)

Add this much extra space between objects that are next to each other horizontally, overriding the padding property value.

X-positions (pair of numbers)

Pair of X staff coordinates of a spanner in the form (left . right), where both left and right are in staff-space units of the current staff.

Y-attachment (number)

Vertical attachment of a line on a frame, typically between -1 (down) and 1 (up).

Y-extent (pair of numbers)

Extent (size) in the Y direction, measured in staff-space units, relative to object’s reference point.

Y-offset (number)

The vertical amount that this object is moved relative to its Y-parent.

Note that many objects have special positioning considerations, which cause any setting of Y-offset to be ignored or modified, even though the object supports the self-alignment-interface.

zigzag-length (dimension, in staff space)

The length of the lines of a zigzag, relative to zigzag-width. A value of 1 gives 60-degree zigzags.

zigzag-width (dimension, in staff space)

The width of one zigzag squiggle. This number is adjusted slightly so that the spanner line can be constructed from a whole number of squiggles.


LilyPond Internals Reference v2.25.21 (development-branch).