Level lines

A level line is a reference line at a fixed value on a range axis. Config lives at annotations.levelLines.<id>.

Unlike arrows, simple level lines are reasonable to hand-author. For label snap / custom number formats, authoring in the editor then exporting is still easiest.

Minimal example

annotations: {
  levelLines: {
    target: {
      id: 'target',
      value: 70,
      color: '#1A1A1A',
      width: 1.5,
      dashArray: '6,4',
      rangeAxis: 'primaryRange',
      labelFontFamily: 'Arial',
      labelFontSize: 10,
      labelFontColor: '#000000',
    },
  },
}

Solid stroke: prefer dashArray: '' (same convention as gridlines).

Fields

Field	Type	Notes
id	string	Should match the map key
value	number	Position on the range axis
color	string	Line color
width	number	Stroke width (px)
dashArray	string	Dash pattern; '' = solid
rangeAxis	'primaryRange' | 'secondaryRange'	Which scale measures value (default primary)
labelPositionIndex	number | null	Horizontal snap for the value label; omit/null for auto edge placement
labelFontFamily / labelFontSize / labelFontColor	string / number / string	Per-line label chrome
labelNumberFormatSpec	object	{ mode: 'custom'|'linked', source?, customFormat } — see Number formats

Shared bag option: annotations.levelLines.fontFamily can set a default label font for all lines.

Chart types

Common on stacked / clustered / 100% bar, waterfall, line, stacked area, scatter, combo, and bar mekko. Orientation-aware: the line follows the range axis (horizontal line on a vertical chart, and the remapped equivalent when orientation flips).

Live patches

annotations deep-merges for nested story maps in many host paths, but the safest pattern for one-off adds is still: read getChartData(), merge the new id into levelLines, then setChartData with the updated map (or replace the whole annotations.levelLines object you want).

See also Arrows.