### 5.1.1 Contexts explained

Contexts are arranged hierarchically:

#### Output definitions - blueprints for contexts

This section explains the relevance of output definitions when working with contexts. Examples for actual output definitions are given later (see Changing all contexts of the same type).

While music written in a file may refer to context types and names, contexts are created only when the music is actually being interpreted. LilyPond interprets music under control of an ‘output definition’ and may do so for several different output definitions, resulting in different output. The output definition relevant for printing music is specified using `\layout`.

A much simpler output definition used for producing Midi output is specified using `\midi`. Several other output definitions are used by LilyPond internally, like when using the part combiner (Automatic part combining) or creating music quotes (Quoting other voices).

Output definitions define the relation between contexts as well as their respective default settings. While most changes will usually be made inside of a `\layout` block, Midi-related settings will only have an effect when made within a `\midi` block.

Some settings affect several outputs: for example, if `autoBeaming` is turned off in some context, beams count as melismata for the purpose of matching music to lyrics as described in Automatic syllable durations. This matching is done both for printed output as well as for Midi. If changes made to `autoBeaming` within a context definition of a `\layout` block are not repeated in the corresponding `\midi` block, lyrics and music will get out of sync in Midi.

#### See also

Installed Files: ‘`ly/engraver-init.ly`’. ‘`ly/performer-init.ly`’.

#### Score - the master of all contexts

This is the top level notation context. No other context can contain a Score context. By default the Score context handles the administration of time signatures and makes sure that items such as clefs, time signatures, and key-signatures are aligned across staves.

A Score context is instantiated implicitly when a `\score {…}` block is processed.

#### Top-level contexts - staff containers

StaffGroup

Groups staves while adding a bracket on the left side, grouping the staves together. The bar lines of the contained staves are connected vertically. `StaffGroup` only consists of a collection of staves, with a bracket in front and spanning bar lines.

ChoirStaff

Identical to `StaffGroup` except that the bar lines of the contained staves are not connected vertically.

GrandStaff

A group of staves, with a brace on the left side, grouping the staves together. The bar lines of the contained staves are connected vertically.

PianoStaff

Just like `GrandStaff`, but with support for instrument names to the left of each system.

#### Intermediate-level contexts - staves

Staff

Handles clefs, bar lines, keys, accidentals. It can contain `Voice` contexts.

RhythmicStaff

Like `Staff` but for printing rhythms. Pitches are ignored when engraving; the notes are printed on one line. The MIDI rendition retains pitches unchanged.

TabStaff

Context for generating tablature. By default lays the music expression out as a guitar tablature, printed on six lines.

DrumStaff

Handles typesetting for percussion. Can contain `DrumVoice`

VaticanaStaff

Same as `Staff`, except that it is designed for typesetting a piece in gregorian style.

MensuralStaff

Same as `Staff`, except that it is designed for typesetting a piece in mensural style.

#### Bottom-level contexts - voices

Voice-level contexts initialise certain properties and start appropriate engravers. A bottom-level context is one without `defaultchild`. While it is possible to let it accept/contain subcontexts, they can only be created and entered explicitly.

Voice

Corresponds to a voice on a staff. This context handles the conversion of dynamic signs, stems, beams, super- and sub-scripts, slurs, ties, and rests. You have to instantiate this explicitly if you require multiple voices on the same staff.

VaticanaVoice

Same as `Voice`, except that it is designed for typesetting a piece in gregorian style.

MensuralVoice

Same as `Voice`, with modifications for typesetting a piece in mensural style.

Lyrics

Corresponds to a voice with lyrics. Handles the printing of a single line of lyrics.

DrumVoice

The voice context used in a percussion staff.

FiguredBass

The context in which `BassFigure` objects are created from input entered in `\figuremode` mode.

TabVoice

The voice context used within a `TabStaff` context. Usually left to be created implicitly.

CueVoice

A voice context used to render notes of a reduced size, intended primarily for adding cue notes to a staff, see Formatting cue notes. Usually left to be created implicitly.

ChordNames

Typesets chord names.

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#### LilyPond — Notation Reference v2.18.2 (稳定分支).