New for specialist notation (LilyPond Changes)

## New for specialist notation

- For consistency with other ancient clefs, five new mensural clefs are available: `"mensural-f2"`, `"mensural-f3"`, `"mensural-f4"` (same as `"mensural-f"`), `"mensural-f5"`, `"mensural-g1"`, `"mensural-g2"` (same as `"mensural-g"`).
- The default time signature and accidental style in a `PetrucciStaff` context is now the same as in `MensuralStaff`.
- White mensural ligatures now support some rare ligatures (semibreves alone or in the middle), and allow tweaks to show some non-necessary stems.

  >     \score {
  >       \relative {
  >         \set Score.timing = ##f
  >         \set Score.measureBarType = #'()
  >         \override NoteHead.style = #'petrucci
  >         \override Staff.TimeSignature.style = #'mensural
  >         \clef "petrucci-c4"
  >         \[ a1 g f e \]
  >         \[ a1 g\longa \]
  >         \[ \tweak left-down-stem ##t a\breve b
  >            \tweak right-down-stem ##t g\longa \]
  >         \[ \tweak right-down-stem ##t b\maxima
  >            \tweak right-up-stem ##t g\longa \]
  >       }
  >       \layout {
  >         \context {
  >           \Voice
  >           \remove Ligature_bracket_engraver
  >           \consists Mensural_ligature_engraver
  >         }
  >       }
  >     }

- The use of the file `gregorian.ly` is deprecated. While still distributed for backward compatibility, it should be replaced with a `VaticanaScore` context together with some manual `\layout` changes (if necessary): code like

  >     \include "gregorian.ly"

  >     \score {
  >       \new VaticanaStaff { ... }
  >     }

  should become

  >     \new VaticanaScore {
  >       \new VaticanaStaff { ... }
  >     }

  >     \layout {
  >       indent = 0
  >       ragged-last = ##t
  >     }

- LilyPond’s ‘arabic’ note name language is deprecated. While still working for backward compatibility (if you load `hel-arabic.ly`), it is recommended to use ‘english’, ‘italiano’, or your preferred note name language instead.
- Defaults for fret labels in fret diagrams have changed.
  - − The default value for `fret-label-vertical-offset` is set to -0.5, which centers the label in the fret space.
  - − The default number format is now `'custom`, with a format string of `"~dfr"` (resulting in ‘3fr’, for example), instead of `'roman-lower`.
- Two new options are available for `fret-diagram-details`:
  - − `string-overhang` allows to define the extension of string lines beyond the last fret line, in multiples of `fret-distance`. Default value 1.
  - − `barre-thickness` defines the thickness of the barre line, in multiples of `dot-radius`. Only defined for `barre-type=straight`. Default value 1.
- The command `\autoBeamOff` now stops auto-beaming immediately. Previously, its effect was delayed if a beam generated by the auto-beamer engraver was still active.
- It is no longer necessary to switch off auto-beaming while using `\crossStaff`.
- The `\upbow` and `\downbow` signs are now properly inverted if used below a staff. As a consequence, the glyphs `scripts.upbow` and `scripts.downbow` have been renamed to `scripts.uupbow` and `scripts.udownbow`, respectively, and the new inverted glyphs are named `scripts.dupbow` and `scripts.ddownbow`.

  >     \relative c' {
  >       f4^\downbow f^\upbow f_\downbow f_\upbow
  >     }

- In lyrics aligned to a melody, extender lines can now be added automatically for words ending in a melisma.

  >     \relative {
  >       d'4 e f4 g8( f
  >       e4 d c2)
  >     }
  >     \addlyrics {
  >       \set autoExtenders = ##t
  >       A me -- lis -- ma.
  >     }

- By default, chord names are now always shown with English pitch names, no longer dependent on `\language`. Similarly, commands like `\germanChords` are no longer dependent on `\language` either.

  This change might cause differences in displayed chord names.

- A new command `\englishChords` is now available, making it possible to switch back to English chord names.
- Some Scheme functions related to chord names have been renamed.

  > old | new
  > --- | ---
  > `note-name->string` | `pitch->name`
  > `alteration->text-accidental-markup` | `accidental->text-markup`
  > `note-name->markup` | `chord-name:markup`
  > `chord-name->german-markup` | `chord-name:german-markup`
  > `note-name->german-markup` | `chord-name:german-lowercase-name-markup`
  > `chord-name->italian-markup` | `chord-name:italian-markup`

  `convert-ly` handles this automatically.

- Two new Scheme functions related to chord names are now available: `pitch->alteration` returns the accidental for a given pitch and language; `chord-name:name-markup` returns note name markup for a given pitch and language.
- LilyPond now follows the Ignatzek chord name scheme more closely. This reverts changes introduced in version 2.15.21 (in 2011), which are now considered as incorrect and/or ambiguous.

  >     oldException = { <c e g b fis'>-\markup \super "lyd" }
  >     chExceptions = #(append (sequential-music-to-chord-exceptions
  >                              oldException #t)
  >                             ignatzekExceptions)

  >     music = { <c e g d'>1 | <c es g f'> | <c e g b fis'> }

  >     \new StaffGroup \with { instrumentName = "old:" }
  >     <<
  >       \new ChordNames \with {
  >         chordNameExceptions = #chExceptions
  >         additionalPitchPrefix = ""
  >       } \music
  >       \new Voice \transpose c c' \music
  >     >>

  >     \new StaffGroup \with { instrumentName = "new:" }
  >     <<
  >       \new ChordNames \music
  >       \new Voice \transpose c c' \music
  >     >>

  >     \layout {
  >       indent = 1\cm
  >       line-width = 9\cm
  >       ragged-right = ##f
  >     }

#### LilyPond Changes v2.26.0 (stable-branch).

- Major changes in LilyPond
  - Notes for source compilation and packagers
- New for musical notation
  - Pitches improvements
  - Rhythm improvements
  - Expressive mark improvements
  - Repeat improvements
  - Editorial annotation improvements
  - Text and font improvements
- New for specialist notation
- Miscellaneous improvements