+ (axes . (0 1))
+ (X-extent-callback . ,Axis_group_interface::group_extent_callback)
+ (Y-extent-callback . ,Axis_group_interface::group_extent_callback)
+ (space-alist . (
+ (clef . (extra-space . 0.5))
+ (key-signature . (extra-space . 0.0))
+ (staff-bar . (extra-space . 0.0))
+ (time-signature . (extra-space . 0.0))
+ (first-note . (fixed-space . 0.0))
+ ))
+ (breakable . #t)
+ (break-align-symbol . ambitus)
+ (break-visibility . ,begin-of-line-visible)
+ (meta . ((interfaces . (axis-group-interface break-aligned-interface ambitus-interface item-interface ))))
+ ))
+
+ (AmbitusLine
+ . (