### 2.9.3 Typesetting mensural music

#### Mensural contexts

The predefined `MensuralVoice` and `MensuralStaff` contexts can be used to engrave a piece in mensural style. These contexts initialize all relevant context properties and grob properties to proper values, so you can immediately go ahead entering the chant, as the following excerpt demonstrates:

>     \score {
>       <<
>         \new MensuralVoice = "discantus" \relative c'' {
>           \hide Score.BarNumber {
>             c1\melisma bes a g\melismaEnd
>             f\breve
>             \[ f1\melisma a c\breve d\melismaEnd \]
>             c\longa
>             c\breve\melisma a1 g1\melismaEnd
>             fis\longa^\signumcongruentiae
>           }
>         }
>         \new Lyrics \lyricsto "discantus" {
>           San -- ctus, San -- ctus, San -- ctus
>         }
>       >>
>     }

#### See also

Music Glossary: mensural notation.

#### Mensural clefs

The following table shows all mensural clefs that are supported via the `\clef` command. Some of the clefs use the same glyph, but differ only with respect to the line they are printed on. In such cases, a trailing number in the name is used to enumerate these clefs, numbered from the lowest to the highest line. You can manually force a clef glyph to be typeset on an arbitrary line, as described in Clef. The note printed to the right side of each clef in the example column denotes the `c'` with respect to that clef.

Petrucci used C clefs with differently balanced left-side vertical beams, depending on which staff line it is printed.

Description | Supported Clefs | Example
mensural C clef | `mensural-c1`, `mensural-c2`, `mensural-c3`, `mensural-c4`, `mensural-c5` |
mensural F clef | `mensural-f` |
mensural G clef | `mensural-g` |
black mensural C clef | `blackmensural-c1`, `blackmensural-c2`, `blackmensural-c3`, `blackmensural-c4`, `blackmensural-c5` |
neomensural C clef | `neomensural-c1`, `neomensural-c2`, `neomensural-c3`, `neomensural-c4` |
petrucci style C clefs, for use on different staff lines (the example shows the 2nd staff line C clef) | `petrucci-c1`, `petrucci-c2`, `petrucci-c3`, `petrucci-c4`, `petrucci-c5` |
petrucci style F clefs, for use on different staff lines (the example shows the 3rd staff line F clef) | `petrucci-f3`, `petrucci-f4`, `petrucci-f5` |
petrucci style G clef | `petrucci-g` |

#### See also

Music Glossary: mensural notation, clef.

Notation Reference: Clef.

#### Known issues and warnings

The mensural g clef is mapped to the Petrucci g clef.

#### Mensural time signatures

There is limited support for mensuration signs (which are similar to, but not exactly the same as time signatures). The glyphs are hard-wired to particular time fractions. In other words, to get a particular mensuration sign with the `\time n/m` command, `n` and `m` have to be chosen according to the following table

Use the `style` property of grob `TimeSignature` to select ancient time signatures. Supported styles are `neomensural` and `mensural`. The above table uses the `neomensural` style. The following examples show the differences in style:

Time signature, gives a general introduction to the use of time signatures.

#### See also

Music Glossary: mensural notation.

Notation Reference: Time signature.

#### Known issues and warnings

Ratios of note durations cannot change with the time signature, as those are not constant. For example, the ratio of 1 breve = 3 semibreves (tempus perfectum) can be made by hand, by setting

>     breveTP = #(ly:make-duration -1 0 3/2)
>     …
>     { c\breveTP f1 }

This sets `breveTP` to 3/2 times 2 = 3 times a whole note.

The `mensural68alt` and `neomensural68alt` symbols (alternate symbols for 6/8) are not addressable with `\time`. Use `\markup {\musicglyph #"timesig.mensural68alt" }` instead.

#### Mensural note heads

For ancient notation, a note head style other than the `default` style may be chosen. This is accomplished by setting the `style` property of the `NoteHead` object to `baroque`, `neomensural`, `mensural`, `petrucci`, `blackpetrucci` or `semipetrucci`.

The `baroque` style differs from the `default` style by:

- Providing a `maxima` note head, and
- Using a square shape for `\breve` note heads.

The `neomensural`, `mensural`, and `petrucci` styles differ from the `baroque` style by:

- Using rhomboidal heads for semibreves and all smaller durations, and
- Centering the stems on the note heads.

The `blackpetrucci` style produces note heads usable in black mensural notation or coloratio sections in white mensural notation. Because note head style does not influence flag count, in this style a semiminima should be notated as `a8*2`, not `a4`, otherwise it will look like a minima. The multiplyer can be different if coloratio is used e.g. to notate triplets.

Use `semipetrucci` style to draw half-colored note heads (breves, longas and maximas).

The following example demonstrates the `petrucci` style:

>     \set Score.skipBars = ##t
>     \autoBeamOff
>     \override NoteHead.style = #'petrucci
>     a'\maxima a'\longa a'\breve a'1 a'2 a'4 a'8 a'16 a'
>     \override NoteHead.style = #'semipetrucci
>     a'\breve*5/6
>     \override NoteHead.style = #'blackpetrucci
>     a'8*4/3 a'
>     \override NoteHead.style = #'petrucci
>     a'\longa

Note head styles, gives an overview of all available note head styles.

#### See also

Music Glossary: mensural notation, note head.

Notation Reference: Note head styles.

#### Mensural flags

Use the `flag-style` property of grob `Stem` to select ancient flags. Besides the `default` flag style, only the `mensural` style is supported.

>     \override Flag.style = #'mensural
>     \override Stem.thickness = #1.0
>     \override NoteHead.style = #'mensural
>     \autoBeamOff
>     c8 d e f c16 d e f c32 d e f s8
>     c'8 d e f c16 d e f c32 d e f

Note that the innermost flare of each mensural flag is vertically aligned with a staff line.

There is no particular flag style for neo-mensural or Petrucci notation. There are no flags in Gregorian chant notation.

#### See also

Music Glossary: mensural notation, flag.

#### Known issues and warnings

Vertically aligning each flag with a staff line assumes that stems always end either exactly on or exactly in the middle of two staff lines. This may not always be true when using advanced layout features of classical notation (which however are typically out of scope for mensural notation).

#### Mensural rests

Use the `style` property of grob `Rest` to select ancient rests. Supported styles are `classical`, `neomensural`, and `mensural`. `classical` differs from the `default` style only in that the quarter rest looks like a horizontally mirrored 8th rest. The `mensural` and the `neomensural` styles mimic the appearance of rests in manuscripts and prints up to the 16th century.

The following example demonstrates the `mensural` and `neomensural` styles:

>     \set Score.skipBars = ##t
>     \override Rest.style = #'classical
>     r\longa^"classical" r\breve r1 r2 r4 r8 r16 s \break
>     \override Rest.style = #'mensural
>     r\longa^"mensural" r\breve r1 r2 r4 r8 r16 s \break
>     \override Rest.style = #'neomensural
>     r\longa^"neomensural" r\breve r1 r2 r4 r8 r16

There are no 32th and 64th rests specifically for the mensural or neo-mensural style. Instead, the rests from the default style will be taken.

#### See also

Music Glossary: mensural notation.

Notation Reference: Rests.

Snippets: Ancient notation.

#### Known issues and warnings

The glyph for the maxima rest in mensural style is actually a perfect longa rest; use two (or three) longa rests to print a maxima rest. Longa rests are not grouped automatically, so have to be done manually by using pitched rests.

#### Mensural accidentals and key signatures

The `mensural` style provides a sharp and a flat sign different from the default style. If called for, the natural sign will be taken from the `vaticana` style.

The style for accidentals and key signatures is controlled by the `glyph-name-alist` property of the grobs `Accidental` and `KeySignature`, respectively; e.g.:

>     \override Staff.Accidental.glyph-name-alist =
>       #alteration-mensural-glyph-name-alist

#### See also

Music Glossary: mensural notation, Pitch names, accidental, key signature.

Notation Reference: Pitches, Accidentals, Automatic accidentals, Key signature.

Internals Reference: KeySignature.

#### Annotational accidentals (musica ficta)

In European music from before about 1600, singers were expected to chromatically alter notes at their own initiative according to certain rules. This is called musica ficta. In modern transcriptions, these accidentals are usually printed over the note.

Support for such suggested accidentals is included, and can be switched on by setting `suggestAccidentals` to true.

    fis gis
    \set suggestAccidentals = ##t
    ais bis

This will treat every subsequent accidental as musica ficta until it is unset with `\set suggestAccidentals = ##f`. A more practical way is to use `\once \set suggestAccidentals = ##t`, which can even be defined as a convenient shorthand:

>     ficta = { \once \set suggestAccidentals = ##t }
>     \score { \relative c''
>       \new MensuralVoice  {
>         \once \set suggestAccidentals = ##t
>         bes4 a2 g2 \ficta fis8 \ficta e! fis2 g1
>       }
>     }

#### See also

Internals Reference: Accidental_engraver, AccidentalSuggestion.

#### White mensural ligatures

There is limited support for white mensural ligatures.

To engrave white mensural ligatures, in the layout block, replace the `Ligature_bracket_engraver` with the `Mensural_ligature_engraver` in the `Voice` context:

>     \layout {
>       \context {
>         \Voice
>         \remove "Ligature_bracket_engraver"
>         \consists "Mensural_ligature_engraver"
>       }
>     }

There is no additional input language to describe the shape of a white mensural ligature. The shape is rather determined solely from the pitch and duration of the enclosed notes. While this approach may take a new user a while to get accustomed to, it has the great advantage that the full musical information of the ligature is known internally. This is not only required for correct MIDI output, but also allows for automatic transcription of the ligatures.

At certain places two consecutive notes can be represented either as two squares or as an oblique parallelogram (flexa shape). In such cases the default is the two squares, but a flexa can be required by setting the `ligature-flexa` property of the second note head. The length of a flexa can be set by the note head property `flexa-width`.

For example,

>     \score {
>       \relative c' {
>         \set Score.timing = ##f
>         \set Score.defaultBarType = "-"
>         \override NoteHead.style = #'petrucci
>         \override Staff.TimeSignature.style = #'mensural
>         \clef "petrucci-g"
>         \[ c'\maxima g \]
>         \[ d\longa
>            \override NoteHead.ligature-flexa = ##t
>            \once \override NoteHead.flexa-width = #3.2
>            c\breve f e d \]
>         \[ c'\maxima d\longa \]
>         \[ e1 a, g\breve \]
>       }
>       \layout {
>         \context {
>           \Voice
>           \remove "Ligature_bracket_engraver"
>           \consists "Mensural_ligature_engraver"
>         }
>       }
>     }

Without replacing `Ligature_bracket_engraver` with `Mensural_ligature_engraver`, the same music transcribes to the following

#### See also

Music Glossary: ligature.

Notation Reference: Gregorian square neume ligatures, Ligatures.

#### Known issues and warnings

Horizontal spacing of ligatures is poor. Accidentals may collide with previous notes.

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