### 3.2.107 spanner-interface

Some objects are horizontally spanned between objects. For example, slurs, beams, ties, etc. These grobs form a subtype called `Spanner`. All spanners have two span points (these must be `Item` objects), one on the left and one on the right. The left bound is also the X reference point of the spanner.

#### User settable properties:

> `normalized-endpoints` (pair)

>   Represents left and right placement over the total spanner, where the width of the spanner is normalized between 0 and 1.

> `minimum-length` (dimension, in staff space)

>   Try to make a spanner at least this long, normally in the horizontal direction. This requires an appropriate callback for the `springs-and-rods` property. If added to a `Tie`, this sets the minimum distance between noteheads.

> `spanner-id` (string)

>   An identifier to distinguish concurrent spanners.

> `to-barline` (boolean)

>   If true, the spanner will stop at the bar line just before it would otherwise stop.

#### Internal properties:

> `spanner-broken` (boolean)

>   Indicates whether spanner alignment should be broken after the current spanner.

This grob interface is used in the following graphical object(s): BassFigureAlignment, BassFigureAlignmentPositioning, BassFigureContinuation, BassFigureLine, Beam, BendAfter, ClusterSpanner, DynamicLineSpanner, DynamicTextSpanner, Episema, FootnoteSpanner, Glissando, GraceSpacing, Hairpin, HorizontalBracket, InstrumentName, KievanLigature, LedgerLineSpanner, LigatureBracket, LyricExtender, LyricHyphen, LyricSpace, MeasureCounter, MeasureGrouping, MensuralLigature, MultiMeasureRest, MultiMeasureRestNumber, MultiMeasureRestText, OttavaBracket, PercentRepeat, PercentRepeatCounter, PhrasingSlur, PianoPedalBracket, Slur, SostenutoPedalLineSpanner, SpacingSpanner, StaffGrouper, StaffSymbol, SustainPedalLineSpanner, System, SystemStartBar, SystemStartBrace, SystemStartBracket, SystemStartSquare, TextSpanner, Tie, TieColumn, TrillSpanner, TupletBracket, TupletNumber, UnaCordaPedalLineSpanner, VaticanaLigature, VerticalAlignment, VerticalAxisGroup, VoiceFollower, VoltaBracket and VoltaBracketSpanner.

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