### 3.2.99 separation-item-interface

Item that computes widths to generate spacing rods.

#### User settable properties:

> `X-extent` (pair of numbers)

>   Extent (size) in the X direction, measured in staff-space units, relative to object’s reference point.

> `padding` (dimension, in staff space)

>   Add this much extra space between objects that are next to each other.

> `horizontal-skylines` (pair of skylines)

>   Two skylines, one to the left and one to the right of this grob.

> `skyline-vertical-padding` (number)

>   The amount by which the left and right skylines of a column are padded vertically, beyond the `Y-extent`s and `extra-spacing-height`s of the constituent grobs in the column. Increase this to prevent interleaving of grobs from adjacent columns.

#### Internal properties:

> `conditional-elements` (array of grobs)

>   Internal use only.

> `elements` (array of grobs)

>   An array of grobs; the type is depending on the grob where this is set in.

This grob interface is used in the following graphical object(s): NonMusicalPaperColumn, NoteColumn and PaperColumn.

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