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Reference lines

A reference line is a line intersecting the chart area from a given point on the measure axis.

You can use a reference line to indicate a certain level of chart data. The reference line is only drawn if it falls within the current range of the measure axis. You can have several reference lines in the same chart.

Reference lines are available from Advanced options in the following visualization types:

- Bar chart
- Box plot
- Combo chart
- Distribution plot
- Gauge
- Histogram
- Line chart
- Scatter plot
- Waterfall chart

## Reference line expression

You can either set the reference line expression to an absolute numeric value, or enter an arbitrary numeric expression.

## Dimensional reference lines

You can also add reference lines along the dimension axis. Both continuous and discrete axes are supported. It is possible to enter text values for discrete dimensional axes, and numerical values or expressions for continuous axes. On a time axis it is possible to enter an expression that gives a time-based result like a date or a month.

Dimensional reference lines are available in the following visualization types:

- Bar chart
- Combo chart
- Line chart