> ## Documentation Index
> Fetch the complete documentation index at: https://cubed3-igor-docs-cartesian-chart-builder.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Line

> Track how a measure changes over time or across an ordered dimension.

Line charts connect data points with a continuous line. Use them when the direction and rate of change matter — trends over time, trajectories of multiple series, or any ordered dimension where continuity is meaningful.

## Variants

### Single series

One measure plotted against a time or ordered dimension. The simplest and most common use case.

### Multi-series

Multiple lines plotted on the same axes. Pick a dimension in the measure's **Break down by** row to split it into one line per dimension value, or add more measures to plot them as separate series.

### With reference line

A reference line marks a target, threshold, or benchmark. Add one from the axis's **Axis actions** menu on the Style tab.

## Line appearance

A line's row in its axis section on the Style tab carries the controls that shape it:

| Control           | Options                                                                                     |
| ----------------- | ------------------------------------------------------------------------------------------- |
| **Line style**    | **Solid**, **Dashed**, **Dotted** — Auto assigns styles by list order                       |
| **Point shape**   | **Circle**, **Square**, **Triangle**, **Diamond**, **None** — Auto draws a marker-free line |
| **Interpolation** | **Linear**, **Step**, **Smooth**                                                            |
| **Trend line**    | A dashed least-squares regression line in the measure's color                               |

Line style earns its keep on a chart where color already belongs to a break-down: it tells the measures apart when their colors cannot.

## Reference lines

Add a reference line from the **Axis actions** menu (⋮) in any axis header on the Style tab. Set the value, label, color, line width, and line style. A labeled line also takes horizontal (start / middle / end) and vertical (above / below) placement for its text. Multiple reference lines are supported on the same axis.

See [Axes & series style](/docs/explore-analyze/charts/configuration/axes) for the full configuration reference.

## Axis behavior

Line charts use a temporal dimension axis for time dimensions — continuous, time-aware, and not constrained to the result set. For non-time dimensions, the axis is ordinal and follows the result set sort order. Gaps in the line indicate missing data points.

A line is drawn against a category axis whenever the chart also draws a bar, so the two marks always agree on the same bands.

## Combining with bars

Add a second measure from the **Measure actions** menu on the Fields tab, set its mark to **Line**, and assign it to the right axis for a dual-axis layout. The chart type reads **Composite** once the marks differ.