LilyPond program-reference: 3.2.7 axis-group-interface

### 3.2.7 axis-group-interface

An object that groups other layout objects.

#### User settable properties:

> `axes` (list)

>   List of axis numbers. In the case of alignment grobs, this should contain only one number.

> `keep-fixed-while-stretching` (boolean)

>   A grob with this property set to true is fixed relative to the staff above it when systems are stretched.

> `max-stretch` (number)

>   The maximum amount that this `VerticalAxisGroup` can be vertically stretched (for example, in order to better fill a page).

> `no-alignment` (boolean)

>   If set, don’t place this grob in a `VerticalAlignment`; rather, place it using its own `Y-offset` callback.

> `vertical-skylines` (unknown)

>   Two skylines, one above and one below this grob.

#### Internal properties:

> `X-common` (layout object)

>   Common reference point for axis group.

> `Y-common` (layout object)

>   See `X-common`.

> `adjacent-pure-heights` (vector)

>   Used by a `VerticalAxisGroup` to cache the `Y-extent`s of different column ranges.

> `elements` (unknown)

>   A list of grobs; the type is depending on the grob where this is set in.

> `pure-Y-common` (layout object)

>   A cache of the `common_refpoint_of_array` of the `elements` grob set.

> `pure-relevant-items` (unknown)

>   A subset of elements that are relevant for finding the `pure-Y-extent`.

> `pure-relevant-spanners` (unknown)

>   A subset of elements that are relevant for finding the `pure-Y-extent`.

This grob interface is used in the following graphical object(s): Ambitus, BassFigureAlignment, BassFigureAlignmentPositioning, BassFigureLine, BreakAlignGroup, BreakAlignment, DotColumn, DynamicLineSpanner, NonMusicalPaperColumn, NoteCollision, NoteColumn, PaperColumn, SostenutoPedalLineSpanner, SustainPedalLineSpanner, System, TrillPitchGroup, UnaCordaPedalLineSpanner, VerticalAlignment, VerticalAxisGroup and VoltaBracketSpanner.

#### Internals Reference