### 1.7.2 Outside the staff

This section discusses how to add emphasis to elements in the staff from outside of the staff.

#### Balloon help

Elements of notation can be marked and named with the help of a square balloon. The primary purpose of this feature is to explain notation.

>     \new Voice \with { \consists "Balloon_engraver" }
>     {
>       \balloonGrobText #'Stem #'(3 . 4) \markup { "I'm a Stem" }
>       a8
>       \balloonGrobText #'Rest #'(-4 . -4) \markup { "I'm a rest" }
>       r
>       <c, g'-\balloonText #'(-2 . -2) \markup { "I'm a note head" } c>2.
>     }

There are two music functions, `balloonGrobText` and `balloonText`; the former is used like `\once \override` to attach text to any grob, and the latter is used like `\tweak`, typically within chords, to attach text to an individual note.

Balloon text does not influence note spacing, but this can be altered:

>     \new Voice \with { \consists "Balloon_engraver" }
>     {
>       \balloonGrobText #'Stem #'(3 . 4) \markup { "I'm a Stem" }
>       a8
>       \balloonGrobText #'Rest #'(-4 . -4) \markup { "I'm a rest" }
>       r
>       \balloonLengthOn
>       <c, g'-\balloonText #'(-2 . -2) \markup { "I'm a note head" } c>2.
>     }

#### Predefined commands

`\balloonLengthOn`, `\balloonLengthOff`.

#### See also

Snippets: Editorial annotations.

Internals Reference: Balloon_engraver, BalloonTextItem, balloon-interface.

#### Grid lines

Vertical lines can be drawn between staves synchronized with the notes.

The `Grid_point_engraver` must be used to create the end points of the lines, while the `Grid_line_span_engraver` must be used to actually draw the lines. By default this centers grid lines horizontally below and to the left side of each note head. Grid lines extend from the middle lines of each staff. The `gridInterval` must specify the duration between the grid lines.

>     \layout {
>       \context {
>         \Staff
>         \consists "Grid_point_engraver"
>         gridInterval = #(ly:make-moment 1/4)
>       }
>       \context {
>         \Score
>         \consists "Grid_line_span_engraver"
>       }
>     }

>     \score {
>       \new ChoirStaff <<
>         \new Staff \relative c'' {
>           \stemUp
>           c4. d8 e8 f g4
>         }
>         \new Staff \relative c {
>           \clef bass
>           \stemDown
>           c4 g' f e
>         }
>       >>
>     }

#### Selected Snippets

Grid lines: changing their appearance

The appearance of grid lines can be changed by overriding some of their properties.

>     \score {
>       \new ChoirStaff <<
>         \new Staff {
>           \relative c'' {
>             \stemUp
>             c'4. d8 e8 f g4
>           }
>         }
>         \new Staff {
>           \relative c {
>             % this moves them up one staff space from the default position
>             \override Score.GridLine.extra-offset = #'(0.0 . 1.0)
>             \stemDown
>             \clef bass
>             \once \override Score.GridLine.thickness = #5.0
>             c4
>             \once \override Score.GridLine.thickness = #1.0
>             g'4
>             \once \override Score.GridLine.thickness = #3.0
>             f4
>             \once \override Score.GridLine.thickness = #5.0
>             e4
>           }
>         }
>       >>
>       \layout {
>         \context {
>           \Staff
>           % set up grids
>           \consists "Grid_point_engraver"
>           % set the grid interval to one quarter note
>           gridInterval = #(ly:make-moment 1/4)
>         }
>         \context {
>           \Score
>           \consists "Grid_line_span_engraver"
>           % this moves them to the right half a staff space
>           \override NoteColumn.X-offset = #-0.5
>         }
>       }
>     }

#### See also

Snippets: Editorial annotations.

Internals Reference: Grid_line_span_engraver, Grid_point_engraver, GridLine, GridPoint, grid-line-interface, grid-point-interface.

#### Analysis brackets

Brackets are used in musical analysis to indicate structure in musical pieces. Simple horizontal brackets are supported.

>     \layout {
>       \context {
>         \Voice
>         \consists "Horizontal_bracket_engraver"
>       }
>     }
>     \relative c'' {
>       c2\startGroup
>       d\stopGroup
>     }

Analysis brackets may be nested.

>     \layout {
>       \context {
>         \Voice
>         \consists "Horizontal_bracket_engraver"
>       }
>     }
>     \relative c'' {
>       c4\startGroup\startGroup
>       d4\stopGroup
>       e4\startGroup
>       d4\stopGroup\stopGroup
>     }

#### See also

Snippets: Editorial annotations.

Internals Reference: Horizontal_bracket_engraver, HorizontalBracket, horizontal-bracket-interface, Staff.

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