New features in 2.20 since 2.18
*******************************

New for musical notation
------------------------

*Displaying pitch improvements*

   • Pitches that have a sharp or flat in their name now need to be
     hyphenated;

          \key a-flat \major

     instead of:

          \key aflat \major

     Pitches that contain _double_ sharps or flats in their name,
     however, do not need a second hyphen.  For example using the Dutch
     notation ‘cisis’:

          \key c-sharpsharp \major

   • Accidental rules can now be defined _across_ ‘ChoirStaff’ contexts.

   • Two new accidental rules have been added.  Both combine the
     characteristics of ‘modern-voice’, ‘piano’ and their equivalents:

     ‘choral’

          image of music

     This is the now the default accidental style for ‘ChoirStaff’.

     ‘choral-cautionary’

          image of music

     The same as ‘choral’ but with the extra accidentals typeset as
     cautionaries instead.

     Also see *note (lilypond-notation)Automatic accidentals::.

   • Four new clef glyphs are now available; ‘GG’ (double-G), ‘Tenor G’,
     ‘varC’ plus related tessitura and ‘Varpercussion’:

     Example                Output         Example                Output
                                                                  
     ----------------------------------------------------------------------------
     ‘\clef GG’             image of music ‘\clef tenorG’         image of music
     ‘\clef varC’           image of music ‘\clef altovarC’       image of music
     ‘\clef tenorvarC’      image of music ‘\clef baritonevarC’   image of music
     ‘\clef                 image of music
     varpercussion’

     Also see *note (lilypond-notation)Clef styles::.

   • French note names are now explicitly defined – previously they were
     aliased to Italian note names.  The D pitch may be entered as
     either ‘re’ or ‘ré’.

          \language "français"
          do ré mi fa | sol la si do | ré1
          image of music

     Double sharps are entered using an ‘x’ suffix.

          \language "français"
          dob, rebb misb fabsb | sold ladd six dosd | rédsd1
          image of music

   *Rhythm improvements*

   • Multi-measure rests have length according to their total duration,
     under the control of ‘MultiMeasureRest.space-increment’.  Note the
     default value is ‘2.0’.

          \compressFullBarRests
          R1*2 R1*4 R1*64 R1*16
          image of music

          \compressFullBarRests
          \override Staff.MultiMeasureRest.space-increment = 2.5
          R1*2 R1*4 R1*64 R1*16
          image of music

   • Improvements to the ‘\partial’ command have been made when used
     with parallel music and/or multiple contexts.

   • It is now possible to change the time signature mid-measure by
     using both the ‘\time’ and ‘\partial’ commands together.

          f f f f | f2. \bar "||"
          \time 3/4 \partial 4
          f8 8 | f2 f8 f |
          image of music

   • Isolated durations in music now stand for unpitched notes.  Pitches
     are taken from the preceding note or chord.  This is especially
     convenient for specifying rhythms in both music and scheme
     functions and can help improve the readability of LilyPond source
     files.

          c64[ 64] 32 16 8^- <g b d>4~ 2 | 1
          image of music

          \new DrumStaff \with { \override StaffSymbol.line-count = 1 }
          \drummode {
            \time 3/4
            tambourine 8 \tuplet 3/2 { 16 16 16 }
                       8 \tuplet 3/2 { 16 16 16 } 8 8 |
          }
          image of music

   • Beaming exceptions can now be constructed using the simpler
     ‘\beamExceptions’ scheme function.  Previously, this would have
     required writing:

          \set Timing.beamExceptions =
          #'(                         ;start of alist
             (end .                   ;entry for end of beams
              (                       ;start of alist of end points
               ((1 . 32) . (2 2 2))   ;rule for 1/32 beams -- end each 1/16
              )))

          \time #'(2 1) 3/16
          c16 c c
          \repeat unfold 6 { c32 }

     With the new ‘\beamExceptions’ scheme function, this becomes:

          \set Timing.beamExceptions =
            \beamExceptions { 32[ 32] 32[ 32] 32[ 32] }

          \time #'(2 1) 3/16
          c16 c c |
          \repeat unfold 6 { c32 } |
          image of music

     with multiple exceptions separated by bar checks.  Note that
     writing the exception pattern without pitches is convenient but not
     mandatory (also see the previous documented rhythm improvement –
     _Isolated durations in music now stand for unpitched notes_.

   • The positioning of tuplet numbers for kneed beams has been
     improved.  Previously, tuplet numbers were placed according to the
     position of the tuplet bracket, even if the bracket was not
     printed.  This could lead to tuplet numbers being ‘stranded’.

     Previously:

          image of music

     Now, when the bracket is not drawn, tuplet numbers are positioned
     closer.

          image of music

   • Collision detection for the kneed beam tuplet numbers has also been
     added, shifting the offset horizontally if the number is too close
     to an adjoining note column (but still preserving the number’s
     vertical distance).  In the event of a collision – for example with
     an accidental – the tuplet number will be shifted vertically
     instead.  If the tuplet number is itself too large to fit within
     the available space, the original, ‘bracket-based’, positioning
     system will be used instead.

          image of music

     The original kneed-beam tuplet behavior is still available with a
     new, ‘knee-to-beam’ property for the ‘TupletNumber’ layout object.

          \time 2/4
          \override Beam.auto-knee-gap = 3
          \override TupletNumber.knee-to-beam = ##f
          \override TupletBracket.bracket-visibility = ##t
          \tuplet 3/2 4 { g8 c'' e, }
          \once \override TupletBracket.bracket-visibility = ##f
          \tuplet 3/2 4 { g,,8 c'' e, }
          image of music

   *Expressive mark improvements*

   • The ends of hairpins may now be fine-tuned using the ‘shorten-pair’
     grob property.  This previously only affected text-spanners (e.g.
     ‘TupletBracket’ and ‘OttavaBracket’).

     Positive and negative values offset right and left respectively.

          \once \override Hairpin.shorten-pair = #'(0 . 2)
          a1\< | a2 a\!

          \once \override Hairpin.shorten-pair = #'(2 . 0)
          \once \override Hairpin.stencil = #constante-hairpin
          a1\< | a2 a\!

          \once \override Hairpin.shorten-pair = #'(-1 . -1)
          \once \override Hairpin.stencil = #flared-hairpin
          a1\< | a2 a\!
          image of music

   • Individual slurs and phrasing slurs may now be started from an
     explicit note within a chord.

          <f a( c>1 | <c') e g(> | <a c) e>
          image of music

          <f( a\( c>1 | <c'\) e\( g> | <a c e\)>
          image of music

   • A new command ‘\=X’ has been added – where ‘X’ can be any
     non-negative integer or symbol – so that a specific ‘id’ can be
     assigned to the start and end of slurs and phrasing slurs.

     This is useful when simultaneous slurs are required or if one slur
     overlaps another or when nesting short slurs within a longer one.

          <a c e\=7\(>1 | <g b d\=£(> |
          <f\=A( a c\="foo"(> | <c'\="foo")\=A) e\=£) g\=7\)> |
          image of music

     Also see *note (lilypond-notation)Expressive marks as curves::.

   *Repeat notation improvements*

   • The visual style of tremolo slashes (shape, style and slope) is now
     more finely controlled.
          image of music

   • The music function ‘\unfoldRepeats’ can now take an optional
     argument-list specifying which type(s) of repeated music should be
     unfolded.  Possible entries are ‘percent’, ‘tremolo’, ‘volta’.  If
     the optional argument-list is unspecified, ‘repeated-music’ will be
     used, unfolding all.

   *Staff notation improvements*

   • A new command ‘\magnifyStaff’ has been added which scales staff
     sizes, staff lines, bar lines, beamlets and horizontal spacing
     generally at the ‘Staff’ context level.  Staff lines are prevented
     from being scaled smaller than the default since the thickness of
     stems, slurs, and the like are all based on the staff line
     thickness.

   • A new command ‘\magnifyMusic’ has been added, which allows the
     notation size to be changed without changing the staff size, while
     automatically scaling stems, beams, and horizontal spacing.

          \new Staff <<
            \new Voice \relative {
              \voiceOne
              <e' e'>4 <f f'>8. <g g'>16 <f f'>8 <e e'>4 r8
            }
            \new Voice \relative {
              \voiceTwo
              \magnifyMusic 0.63 {
                \override Score.SpacingSpanner.spacing-increment = #(* 1.2 0.63)
                r32 c'' a c a c a c r c a c a c a c
                r c a c a c a c a c a c a c a c
              }
            }
          >>
          image of music

   • A new command, ‘\RemoveAllEmptyStaves’, has been made available,
     which acts exactly like ‘\RemoveEmptyStaves’, except for also
     removing empty staves on the first system in a score.

   • A new markup command ‘\justify-line’ has been added.  Similar to
     the ‘\fill-line’ markup command except that instead of setting
     _words_ in columns, the ‘\justify-line’ command balances the
     whitespace between them ensuring that when there are three or more
     words in a markup, the whitespace is always consistent.

          \markup \fill-line {oooooo oooooo oooooo oooooo}
          \markup \fill-line {ooooooooo oooooooo oo ooo}
          image of music

          \markup \justify-line {oooooo oooooo oooooo oooooo}
          \markup \justify-line {ooooooooo oooooooo oo ooo}
          image of music

   *Editorial annotation improvements*

   • It is now possible to add text to analysis brackets through the
     ‘HorizontalBracketText’ object.
          \layout {
            \context {
              \Voice
              \consists "Horizontal_bracket_engraver"
            }
          }

          {
            \once \override HorizontalBracketText.text = "a"
            c''\startGroup d''\stopGroup
            e''-\tweak HorizontalBracketText.text "a'" \startGroup d''\stopGroup
          }
          image of music

   *Text formatting improvements*

   • Support for making it easier to use alternative ‘music’ fonts other
     than the default Emmentaler in LilyPond has been added.  See *note
     (lilypond-notation)Replacing the notation font:: for more
     information.

   • Default text fonts have been changed from ‘Century Schoolbook L’,
     ‘sans-serif’, and ‘monospace’.

     For ‘svg’ backend:
     Family      Default font
     -----------------------------------
     _roman_     ‘serif’
     _sans_      ‘sans-serif’
     _typewriter_‘monospace’

     ‘serif’, ‘sans-serif’, and ‘monospace’ are ‘generic-family’ in SVG
     and CSS specifications.

     For other backends:
     Family      Default font (alias)   Alias definition lists
     ----------------------------------------------------------------------------
     _roman_     ‘LilyPond Serif’       TeX Gyre Schola, C059, Century
                                        SchoolBook URW, Century Schoolbook L,
                                        DejaVu Serif, ..., serif
     _sans_      ‘LilyPond Sans         TeX Gyre Heros, Nimbus Sans, Nimbus
                 Serif’                 Sans L, DejaVu Sans, ..., sans-serif
     _typewriter_‘LilyPond Monospace’   TeX Gyre Cursor, Nimbus Mono PS,
                                        Nimbus Mono, Nimbus Mono L, DejaVu
                                        Sans Mono, ..., monospace

     ‘LilyPond Serif’, ‘LilyPond Sans Serif’, and ‘LilyPond Monospace’
     are font aliases defined in the LilyPond dedicated FontConfig
     configuration file ‘00-lilypond-fonts.conf’.  Where a character
     dosen’t exist in the first font listed, the next font listed will
     be used instead for that character.  For details of alias
     definitions, please see to ‘00-lilypond-fonts.conf’ under the
     installed directory.

   • When using OpenType fonts, font features can be used.  Note: Not
     all OpenType fonts have all functions.

          % True small caps
          \markup { Normal Style: Hello HELLO }
          \markup { \caps { Small Caps: Hello } }
          \markup { \override #'(font-features . ("smcp"))
                    { True Small Caps: Hello } }

          % Number styles
          \markup { Normal Number Style: 0123456789 }
          \markup { \override #'(font-features . ("onum"))
                    { Old Number Style: 0123456789 } }

          % Stylistic Alternates
          \markup { \override #'(font-features . ("salt 0"))
                    { Stylistic Alternates 0: εφπρθ } }
          \markup { \override #'(font-features . ("salt 1"))
                    { Stylistic Alternates 1: εφπρθ } }

          % Multiple features
          \markup { \override #'(font-features . ("onum" "smcp" "salt 1"))
                    { Multiple features: Hello 0123456789 εφπρθ } }
          image of music

   • Two new styles of whiteout are now available.  The ‘outline’ style
     approximates the contours of a glyph’s outline, and its shape is
     produced from multiple displaced copies of the glyph.  The
     ‘rounded-box’ style produces a rounded rectangle shape.  For all
     three styles, including the default ‘box’ style, the whiteout
     shape’s ‘thickness’, as a multiple of staff-line thickness, can be
     customized.

          \markup {
            \combine
              \filled-box #'(-1 . 15) #'(-3 . 4) #1
              \override #'(thickness . 3)
              \whiteout whiteout-box
          }
          \markup {
            \combine
              \filled-box #'(-1 . 24) #'(-3 . 4) #1
              \override #'(style . rounded-box)
              \override #'(thickness . 3)
              \whiteout whiteout-rounded-box
          }
          \markup {
            \combine
              \filled-box #'(-1 . 18) #'(-3 . 4) #1
              \override #'(style . outline)
              \override #'(thickness . 3)
              \whiteout whiteout-outline
          }
          \relative {
            \override Staff.Clef.whiteout-style = #'outline
            \override Staff.Clef.whiteout = 3
            g'1
          }
          image of music

   • A new markup-command, ‘\with-dimensions-from’, makes
     ‘\with-dimensions’ easier to use by taking the new dimensions from
     a markup object, given as first argument.
          \markup {
            \pattern #5 #Y #0 "x"
            \pattern #5 #Y #0 \with-dimensions-from "x" "f"
            \pattern #5 #Y #0 \with-dimensions-from "x" "g"
            \override #'(baseline-skip . 2)
            \column {
              \pattern #5 #X #0 "n"
              \pattern #5 #X #0 \with-dimensions-from "n" "m"
              \pattern #5 #X #0 \with-dimensions-from "n" "!"
            }
          }
          image of music

   • Markup-command ‘\draw-squiggle-line’ is now available.  Customizing
     is possible with overrides of ‘thickness’, ‘angularity’, ‘height’
     and ‘orientation’
          \markup
            \overlay {
              \draw-squiggle-line #0.5 #'(3 . 3) ##t

              \translate #'(3 . 3)
              \override #'(thickness . 4)
              \draw-squiggle-line #0.5 #'(3 . -3) ##t

              \translate #'(6 . 0)
              \override #'(angularity . -5)
              \draw-squiggle-line #0.5 #'(-3 . -3) ##t

              \translate #'(3 . -3)
              \override #'(angularity . 2)
              \override #'(height . 0.3)
              \override #'(orientation . -1)
              \draw-squiggle-line #0.2 #'(-3 . 3) ##t
            }
          image of music

   • Markup-commands ‘\undertie’ and ‘\overtie’ are now available, as
     well as the generic markup-command ‘\tie’.
          \markup {
            \undertie "undertied"
            \overtie "overtied"
          }

          m = {
            c''1 \prall -\tweak text \markup \tie "131" -1
          }

          { \voiceOne \m \voiceTwo \m }
          image of music

New for specialist notation
---------------------------

*Vocal music improvements*

   • A new flexible template suitable for a range of choral music, is
     now provided.  This may be used to create simple choral music, with
     or without piano accompaniment, in two or four staves.  Unlike
     other templates, this template is ‘built-in’, which means it does
     not need to be copied and edited: instead it is simply ‘\include’’d
     in the input file.  For details, see *note
     (lilypond-learning)Built-in templates::.

   • The ‘\addlyrics’ function now works with arbitrary contexts
     incuding ‘Staff’.

   • ‘\lyricsto’ and ‘\addLyrics’ have been ‘harmonized’.  Both now
     accept the same kind of delimited argument list that ‘\lyrics’ and
     ‘\chords’ accept.  Backward compatibility has been added so music
     identifiers (i.e.  ‘\mus’) are permitted as arguments.  A
     ‘convert-ly’ rule has been added that removes redundant uses of
     ‘\lyricmode’ and rearranges combinations with context starters such
     that ‘\lyricsto’ in general is applied last (i.e.  like
     ‘\lyricmode’ would be).

   *Unfretted and fretted string instrument improvements*

   • A new note head style for Tabulature has been added –
     ‘TabNoteHead.style = #'slash’.

   • In fret-diagrams the distance between frets and the distance
     between strings is now independently adjustable.  Available are
     ‘fret-distance’ and ‘string-distance’ as subproperties of
     ‘fret-diagram-details’.
          fretMrkp = \markup { \fret-diagram-terse #"x;x;o;2;3;2;" }

          \markuplist
          \override #'(padding . 2)
          \table #'(0 -1) {
            "default"

            \fretMrkp

            "fret-distance"

            \override #'(fret-diagram-details . ((fret-distance . 2)))
            \fretMrkp

            "string-distance"

            \override #'(fret-diagram-details . ((string-distance . 2)))
            \fretMrkp
          }
          image of music

   • It is now possible to individually color both the dots and
     parentheses in fret diagrams when using the ‘\fret-diagram-verbose’
     markup command.

          \new Voice {
            c1^\markup {
              \override #'(fret-diagram-details . (
                           (finger-code . in-dot))) {
                \fret-diagram-verbose #'((mute 6)
                                         (place-fret 5 3 1 red)
                                         (place-fret 4 5 2 inverted)
                                         (place-fret 3 5 3 green)
                                         (place-fret 2 5 4 blue inverted)
                                         (place-fret 1 3 1 violet)
                                         (barre 5 1 3 ))
              }
            }
            c1^\markup {
              \override #'(fret-diagram-details . (
                           (finger-code . below-string))) {
                \fret-diagram-verbose #'((mute 6)
                                       (place-fret 5 3 1 red parenthesized)
                                       (place-fret 4 5 2 yellow
                                                         default-paren-color
                                                         parenthesized)
                                       (place-fret 3 5 3 green)
                                       (place-fret 2 5 4 blue )
                                       (place-fret 1 3 1)
                                       (barre 5 1 3))
              }
            }
          }
          image of music

   • Two new properties have been added for use in
     ‘fret-diagram-details’ when using the ‘\fret-diagram-verbose’
     markup command; ‘fret-label-horizontal-offset’ which affects the
     ‘fret-label-indication’ and ‘paren-padding’ which controls the
     space between the dot and the parentheses surrounding it.

          \new Voice {
            c1^\markup {
              \fret-diagram-verbose #'((mute 6)
                                       (place-fret 5 3 1)
                                       (place-fret 4 5 2)
                                       (place-fret 3 5 3)
                                       (place-fret 1 6 4 parenthesized)
                                       (place-fret 2 3 1)
                                       (barre 5 2 3))
            }
            c1^\markup {
              \override #'(fret-diagram-details . (
                           (fret-label-horizontal-offset . 2)
                           (paren-padding . 0.25))) {
                \fret-diagram-verbose #'((mute 6)
                                         (place-fret 5 3 1)
                                         (place-fret 4 5 2)
                                         (place-fret 3 5 3)
                                         (place-fret 1 6 4 parenthesized)
                                         (place-fret 2 3 1)
                                         (barre 5 2 3))
              }
            }
          }
          image of music

   • Additional bass strings (for lute tablature) are supported.
          m = { f'4 d' a f d a, g, fis, e, d, c,  \bar "|." }

          \score {
            \new TabStaff \m
            \layout {
              \context {
                \Score
                tablatureFormat = #fret-letter-tablature-format
              }
              \context {
                \TabStaff
                stringTunings = \stringTuning <a, d f a d' f'>
                additionalBassStrings = \stringTuning <c, d, e, fis, g,>
                fretLabels = #'("a" "b" "r" "d" "e" "f" "g" "h" "i" "k")
              }
            }
          }
          image of music

   • String numbers can now also be used to print roman numerals (e.g.
     for unfretted string instruments).
          c2\2
          \romanStringNumbers
          c\2
          \arabicStringNumbers
          c1\3
          image of music

   • ‘TabStaff’ is now able to print micro-tones for bendings etc.
          \layout {
            \context {
              \Score
              supportNonIntegerFret = ##t
            }
          }

          mus = \relative { c'4 cih d dih }

          <<
            \new Staff << \clef "G_8" \mus >>
            \new TabStaff \mus
          >>
          image of music

   *Chord notation improvements*

   • ‘\chordmode’ can now use ‘< >’ and ‘<< >>’ constructs.

   • It is now possible to override the ‘text’ property of chord names.

          <<
          \new ChordNames \chordmode {
            a' b c:7
            \once \override ChordName.text = #"foo"
            d
          }
          >>
          image of music

New for input and output
------------------------

*Input structure improvements*

   • Blocks introduced with ‘\header’ can be stored in variables and
     used as arguments to music and scheme functions and as the body of
     ‘#{...#}’ constructs.  They are represented as a Guile module.

     While ‘\book’, ‘\bookpart’, ‘\score’, ‘\with’, ‘\layout’, ‘\midi’,
     ‘\paper’ blocks can be passed around in similar manner, they are
     represented by different data types.

   *Titles and header improvements*

   • Page numbers may now be printed in roman numerals, by setting the
     ‘page-number-type’ paper variable.

   *Input file improvements*

   • A new command ‘\tagGroup’ has now been added.  This complements the
     existing ‘\keepWithTag’ and ‘\removeWithTag’ commands.  For
     Example:

          \tagGroup #'(violinI violinII viola cello)

     declares a list of ‘tags’ that belong to a single ‘tag group’.

          \keepWithTag #'violinI

     Is now only concerned with ‘tags’ from ‘violinI’’s tag group.

     Any element of the included music tagged with one or more tags from
     the group, but _not_ with VIOLINI, will be removed.

   *Output improvements*

   • LilyPond source files may now be embedded inside the generated PDF
     files.  This experimental feature is disabled by default and may be
     regarded as unsafe, as PDF documents with hidden content tend to
     present a security risk.  Please note that not all PDF viewers have
     the ability to handle embedded documents (if not, the PDF output
     will appear normally and source files will remain invisible).  This
     feature only works with the PDF backend.

   • The ‘output-classic-framework’ procedure and the ‘-dclip-systems’
     are now available with the ‘SVG’ backend.

   • An argument, ‘-dcrop’, has been added, formatting ‘SVG’ and ‘PDF’
     output without margins or page-breaks.

   • A new ‘output-attributes’ grob property is now used for svg output
     instead of the ‘id’ grob property.  It allows multiple attributes
     to be defined as an association list.  For example, ‘#'((id . 123)
     (class . foo) (data-whatever . “bar”))’ will produce the following
     group tag in an SVG file: ‘<g id=“123” class=“foo”
     data-whatever=“bar”> ... </g>’.

   • The PostScript functionality of stroke adjustment is no longer
     applied automatically but left to the discretion of the PostScript
     device (by default, Ghostscript uses it for resolutions up to
     150dpi when generating raster images).  When it is enabled, a more
     complex drawing algorithm designed to benefit from stroke
     adjustment is employed mostly for stems and bar lines.

     Stroke adjustment can be forced by specifying the command line
     option ‘-dstrokeadjust’ to LilyPond.  When generating ‘PDF’ files,
     this will usually result in markedly better looking ‘PDF’ previews
     but significantly larger file size.  Print quality at high
     resolutions will be unaffected.

   • Added a new ‘make-path-stencil’ function that supports all ‘path’
     commands both relative and absolute:

     ‘lineto’, ‘rlineto’, ‘curveto’, ‘rcurveto’, ‘moveto’, ‘rmoveto’,
     ‘closepath’.  The function also supports ‘single-letter’ syntax
     used in standard SVG path commands:

     ‘L’, ‘l’, ‘C’, ‘c’, ‘M’, ‘m’, ‘Z’ and ‘z’.  The new command is also
     backward-compatible with the original ‘make-connected-path-stencil’
     function.  Also see ‘scm/stencil.scm’.

   *MIDI improvements*

   • The most common articulations are now reflected in MIDI output.
     Accent and marcato make notes louder; staccato, staccatissimo and
     portato make them shorter.  Breath marks shorten the previous note.

     This behavior is customizable through the ‘midiLength’ and
     ‘midiExtraVelocity’ properties on ‘ArticulationEvent’.  See
     ‘script-init.ly’ for examples.

   • Improved MIDI output for breathe marks.  After tied notes, breaths
     take time _only_ from the last note of the tie; e.g.  ‘{ c4~ c8
     \breathe }’ performs as ‘{ c4~ c16 r }’ instead of ‘{ c4 r8 }’.
     This is more consistent with articulations and how humans interpret
     breaths after ties.  It now also makes it easier to align
     simultaneous breathe marks over multiple parts, all with different
     note lengths.

   • There is now support for controlling the ‘expression level’ of MIDI
     channels using the ‘Staff.midiExpression’ context property.  This
     can be used to alter the perceived volume of even sustained notes
     (albeit in a very ‘low-level’ way) and accepts a number value
     between ‘0.0’ and ‘1.0’.

          \score {
            \new Staff \with {
              midiExpression = #0.6
              midiInstrument = #"clarinet"
            }
            <<
              { a'1~ a'1 }
              {
                \set Staff.midiExpression = #0.7 s4\f\<
                \set Staff.midiExpression = #0.8 s4
                \set Staff.midiExpression = #0.9 s4
                \set Staff.midiExpression = #1.0 s4

                \set Staff.midiExpression = #0.9 s4\>
                \set Staff.midiExpression = #0.8 s4
                \set Staff.midiExpression = #0.7 s4
                \set Staff.midiExpression = #0.6 s4\!
              }
            >>
            \midi { }
          }

   • When outputting MIDI, LilyPond will now store the ‘title’ defined
     in a score’s ‘\header’ block (or, if there is no such definition on
     the ‘\score’ level, the first such definition found in a ‘\header’
     block of the score’s enclosing ‘\bookpart’, ‘\book’, or top-level
     scope) as the name of the MIDI sequence in the MIDI file.
     Optionally, the name of the MIDI sequence can be overridden using
     the new ‘midititle’ ‘\header’ field independently of ‘title’ (for
     example, in case ‘title’ contains markup code which does not render
     as plain text in a satisfactory way automatically).

   *Extracting music improvements*

   • ‘\displayLilyMusic’ and its underlying Scheme functions no longer
     omit redundant note durations.  This makes it easier to reliably
     recognize and format standalone durations in expressions like
          { c4 d4 8 }

New for spacing issues
----------------------

*Page breaking improvements*

   • There are two new page breaking functions.  ‘ly:one-page-breaking’
     automatically adjusts the height of the page to fit the music, so
     that everything fits on one page.
     ‘ly:one-line-auto-height-breaking’ is like ‘ly:one-line-breaking’,
     placing the music on a single line and adjusting the page width
     accordingly, however it also automatically adjusts the page height
     to fit the music.

   *Vertical and Horizontal spacing improvements*

   • It is now possible to move systems with reference to their current
     position using the ‘extra-offset’ subproperty of
     ‘NonMusicalPaperColumn.line-break-system-details’.  Both vertical
     and horizontal changes are possible.  This feature is especially
     useful for making slight adjustments to the default vertical
     position of individual systems.  See *note
     (lilypond-notation)Explicit staff and system positioning:: for more
     information.

   • Improved visual spacing of small and regular ‘MI’ Funk and Walker
     noteheads so they are now the same width as other shaped notes in
     their respective sets.  ‘SOL’ noteheads are also now visually
     improved when used with both the normal Aiken and Sacred Harp
     heads, as well as with the thin variants.

   • ‘LeftEdge’ now has a definable ‘Y-extent’ (i.e.vertical).  See
     *note (lilypond-internals)LeftEdge::.

   • Grobs and their parents can now be aligned separately allowing more
     flexibility for grob positions.  For example the ‘left’ edge of a
     grob can now be aligned on the ‘center’ of its parent.

   • Improved horizontal alignment when using ‘TextScript’, with
     ‘DynamicText’ or ‘LyricText’.

New for changing defaults
-------------------------

   • All of ‘\override’, ‘\revert’, ‘\set’, and ‘\unset’ now work with
     the ‘\once’ prefix for making one-time settings.
          \relative {
            c'4 d
            \override NoteHead.color = #red
            e4 f |
            \once \override NoteHead.color = #green
            g4 a
            \once \revert NoteHead.color
            b c |
            \revert NoteHead.color
            f2 c |
          }
          image of music

New for Internal interfaces and functions
-----------------------------------------

   • The music and grob property ‘spanner-id’, used for distinguishing
     simultaneous slurs and phrasing slurs, has been changed from a
     string to a _key_ which can be either a non-negative integer or
     symbol (also see the previous documented expressive mark
     improvement – _A new command \=X has been added_).

   • Context properties named in the ‘alternativeRestores’ property are
     restored to their value at the start of the _first_ alternative in
     all subsequent alternatives.

     Currently the default set restores ‘current meter’:

          \time 3/4
          \repeat volta 2 { c2 e4 | }
          \alternative {
            { \time 4/4 f2 d | }
            { f2 d4 | }
          }
          g2. |
          image of music

     ‘measure position’:

          \time 3/4
          \repeat volta 2 { c2 e4 | }
          \alternative {
            { \time 4/4
              \set Timing.measurePosition = #(ly:make-moment -1/2)
              f2 | }
            { f2 d4 | }
          }
          g2. |
          image of music

     and ‘chord changes’:

          <<
            \new ChordNames {
              \set chordChanges = ##t
              \chordmode { c1:m d:m c:m d:m }
            }
            \new Staff {
              \repeat volta 2 { \chordmode { c1:m } }
              \alternative {
                { \chordmode { d:m } }
                { \chordmode { c:m } }
              }
            \chordmode { d:m }
          }
          >>
          image of music

   • LilyPond functions defined with ‘define-music-function’,
     ‘define-event-function’, ‘define-scheme-function’ and
     ‘define-void-function’ can now be directly called from Scheme as if
     they were genuine Scheme procedures.  Argument checking and
     matching will still be performed in the same manner as when calling
     the function through LilyPond input.  This includes the insertion
     of defaults for optional arguments not matching their predicates.
     Instead of using ‘\default’ in the actual argument list for
     explicitly skipping a sequence of optional arguments,
     ‘*unspecified*’ can be employed.

   • Current input location and parser are now stored in GUILE fluids
     and can be referenced via the function calls ‘(*location*)’ and
     ‘(*parser*)’.  Consequently, a lot of functions previously taking
     an explicit ‘parser’ argument no longer do so.

     Functions defined with ‘define-music-function’,
     ‘define-event-function’, ‘define-scheme-function’ and
     ‘define-void-function’ no longer use ‘parser’ and ‘location’
     arguments.

     With those particular definitions, LilyPond will try to recognize
     legacy use of ‘parser’ and ‘location’ arguments, providing
     backwards-compatible semantics for some time.

   • Scheme functions and identifiers can now be used as output
     definitions.

   • Scheme expressions can now be used as chord constituents.

   • Music (and scheme and void) functions and markup commands that just
     supply the final parameters to a chain of overrides, music function
     and markup command calls can now be defined in the form of just
     writing the expression cut short with ‘\etc’.

          \markup bold-red = \markup \bold \with-color #red \etc
          highlight = \tweak font-size 3 \tweak color #red \etc

          \markup \bold-red "text"
          \markuplist \column-lines \bold-red { One Two }

          { c' \highlight d' e'2-\highlight -! }
          image of music

   • Dot-separated symbol lists like ‘FretBoard.stencil’ were already
     supported as of version 2.18.  They may now also contain unsigned
     integers, and may alternatively be separated by commata.  This
     allows usage such as
          { \time 2,2,1 5/8  g'8 8 8 8 8 }
          image of music

     and
          \tagGroup violin,oboe,bassoon

   • Such lists may also be used in expressions for assignments, sets,
     and overrides.  This allows usage such as
          { \unset Timing.beamExceptions
            \set Timing.beatStructure = 1,2,1
            g'8 8 8 8 8 8 8 8 }
          image of music

   • Association list elements could previously be assigned values
     individually (for example, paper variables like
     ‘system-system-spacing.basic-distance’).  They may now be also
     referenced in this manner, as with
          \paper {
            \void \displayScheme \system-system-spacing.basic-distance
          }

     In combination with the previously mentioned changes, this allows
     setting and referencing pseudovariables like ‘violin.1’.

   • The markup-list-command ‘\table’ is now available.  Each column may
     be aligned differently.
          \markuplist {
              \override #'(padding . 2)
              \table
                #'(0 1 0 -1)
                {
                  \underline { center-aligned right-aligned center-aligned left-aligned }
                  one "1" thousandth "0.001"
                  eleven "11" hundredth "0.01"
                  twenty "20" tenth "0.1"
                  thousand "1000" one "1.0"
                }
          }
          image of music

   • ‘InstrumentName’ now supports ‘text-interface’.

   • The ‘thin-kern’ property of the ‘BarLine’ grob has been renamed to
     ‘segno-kern’.

   • ‘KeyCancellation’ grobs now ignore cue clefs (like ‘KeySignature’
     grobs do).

   • Add support for ‘\once \unset’

