### 3.2.24 dot-column-interface

Group dot objects so they form a column, and position dots so they do not clash with staff lines.

#### User settable properties:

> `direction` (direction)

>   If `side-axis` is `0` (or `X`), then this property determines whether the object is placed `LEFT`, `CENTER` or `RIGHT` with respect to the other object. Otherwise, it determines whether the object is placed `UP`, `CENTER` or `DOWN`. Numerical values may also be used: `UP`=`1`, `DOWN`=`-1`, `LEFT`=`-1`, `RIGHT`=`1`, `CENTER`=`0`.

#### Internal properties:

> `dots` (array of grobs)

>   Multiple `Dots` objects.

> `positioning-done` (boolean)

>   Used to signal that a positioning element did its job. This ensures that a positioning is only done once.

> `note-collision` (graphical (layout) object)

>   The `NoteCollision` object of a dot column.

This grob interface is used in the following graphical object(s): DotColumn.

#### Internals Reference v2.18.2 (稳定分支).