### 2.9.2 Ancient notation—common features

#### Pre-defined contexts

For Gregorian chant and mensural notation, there are pre-defined voice and staff contexts available, which set all the various notation signs to values suitable for these styles. If one is satisfied with these defaults, one can proceed directly with note entry without worrying about the details on how to customize a context. See one of the pre-defined contexts `VaticanaVoice`, `VaticanaStaff`, `MensuralVoice`, and `MensuralStaff`. See further

- Gregorian chant contexts,
- Mensural contexts.

#### See also

Music Glossary: mensural notation.

Notation Reference: Gregorian chant contexts, Mensural contexts.

#### Ligatures

A ligature is a graphical symbol that represents at least two distinct notes. Ligatures originally appeared in the manuscripts of Gregorian chant notation to denote ascending or descending sequences of notes on the same syllable. They are also used in mensural notation.

Ligatures are entered by enclosing them in `\[` and `\]`. Some ligature styles may need additional input syntax specific for this particular type of ligature. By default, the `LigatureBracket` engraver just puts a square bracket above the ligature.

>     \relative c'' {
>       \[ g c, a' f d' \]
>       a g f
>       \[ e f a g \]
>     }

Two other ligature styles are available: the Vaticana for Gregorian chant, and the Mensural for mensural music (only white mensural ligatures are supported for mensural music, and with certain limitations). To use any of these styles, the default `Ligature_bracket_engraver` has to be replaced with one of the specialized ligature engravers in the `Voice` context, as explained in White mensural ligatures and Gregorian square neume ligatures.

#### See also

Music Glossary: ligature.

Notation Reference: White mensural ligatures, Gregorian square neume ligatures.

#### Known issues and warnings

Ligatures need special spacing that has not yet been implemented. As a result, there is too much space between ligatures most of the time, and line breaking often is unsatisfactory. Also, lyrics do not correctly align with ligatures.

Accidentals must not be printed within a ligature, but instead need to be collected and printed in front of it.

The syntax still uses the deprecated infix style `\[ music expr \]`. For consistency reasons, it will eventually be changed to postfix style `note\[ … note\]`.

#### Custodes

A custos (plural: custodes; Latin word for “guard”) is a symbol that appears at the end of a staff. It anticipates the pitch of the first note of the following line, thus helping the performer to manage line breaks during performance.

Custodes were frequently used in music notation until the seventeenth century. Nowadays, they have survived only in a few particular forms of musical notation such as contemporary editions of Gregorian chant like the Editio Vaticana. There are different custos glyphs used in different flavors of notational style.

For typesetting custodes, just put a `Custos_engraver` into the `Staff` context when declaring the `\layout` block, and change the style of the custos with an `\override` if desired, as shown in the following example:

The custos glyph is selected by the `style` property. The styles supported are `vaticana`, `medicaea`, `hufnagel`, and `mensural`. They are demonstrated in the following fragment.

#### See also

Music Glossary: custos.

Snippets: Ancient notation.

Internals Reference: Custos.

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