### 3.1.28 ClusterSpannerBeacon

ClusterSpannerBeacon objects are created by: Cluster_spanner_engraver.

Standard settings:

> `Y-extent` (pair of numbers):

>   `ly:cluster-beacon::height`

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

This object supports the following interface(s): cluster-beacon-interface, grob-interface, item-interface and rhythmic-grob-interface.

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