Overview
The Chart block provides two distinct mechanisms for marking up chart content with additional text:
Data Labels — show the numeric value (or a formatted string) directly on each data point, bar, or line marker. Configured per series. Available on most chart types.
Annotations / Data Callout — static or data-bound text boxes that point to specific data points on a chart. Available on the Column chart only. Used to call attention to a specific value (e.g., "Product Launch" on a specific date).
Warning: The Annotation / Data Callout feature is only available on Column chart type. Bar, Line, Scatter, and other types support Data Labels but not Annotations.
Data Labels
Data labels render a text element adjacent to each data point in a series. They eliminate the need for users to hover to see values.
Enabling Data Labels
Open the Chart block's series configuration for the target series.
Enable the Data Labels toggle on the series.
Configure content, format, and position.
Data Label Properties
| Property | Options / Default | Description |
| Content | value / custom expression | What to display. Default is the series value. You can write a custom expression to show formatted text, percentages, or computed strings. |
| Format | number format string | Number formatting for the value (e.g., $#,##0 for currency, 0.0% for percentages). |
| Position | top, bottom, inside, outside, left, right, middle | Where the label is placed relative to the data point or bar. Available positions depend on chart type. |
| Overlap | toggle | When disabled (default), overlapping labels are automatically hidden to reduce clutter. Enable to force all labels to show even when they overlap. |
| Font / Color | font size, color | Label text styling. |
Supported Chart Types
| Chart Type | Data Labels | Notes |
| Column | Yes | Position: top, inside, middle, bottom |
| Bar | Yes | Position: left, right, inside, outside |
| Line | Yes | Labels appear at each marker point |
| Area | Yes | Labels appear at each marker point |
| Scatter | Yes | Labels appear next to each point |
| Pie | Limited | Use Total toggle or Center slot instead |
| Heat Map | Yes (Show Cell Labels) | See Heatmap page |
Annotations (Data Callout)
Annotations let you attach a text callout box with an arrow to a specific data point on a Column chart. The annotation points to the X/Y coordinate of the data point and shows a custom label — typically used to mark an event, milestone, or inflection point.
Tip: Add an annotation to mark a product launch date, a campaign start, or a policy change on a time-series column chart so viewers can see exactly when events occurred relative to the data trend.
Adding an Annotation
Open Annotations: In the Chart block's Content configuration, find the Annotations (or Data Callout) section. Click Add Annotation.
Target the data point: Set the X Value to match the category or date of the column you want to annotate. This must exactly match a value present in your X axis data.
Set the annotation text: Enter the Label to display in the callout. You can bind this dynamically or write a static string.
Configure appearance: Set callout arrow direction, background color, and font style for the annotation box.
Annotation Properties
| Property | Description |
| X Value | The X-axis category or date value to target. Must exactly match a value in the data. |
| Series | Which series the annotation points to (determines the Y position of the arrow tip). |
| Label | The text to display in the annotation callout box. |
| Arrow Direction | Which direction the callout arrow points: up, down, left, right. |
| Background Color | Fill color for the callout box. |
| Text Color | Color for the annotation label text. |
Behavior & Gotchas
⚠ Dense data causes label overlap
When there are many data points, data labels will overlap. The Overlap toggle controls whether they auto-hide in this case. For dense charts, rely on tooltips for detail and use data labels only for sparse key series.
⚠ Annotation X Value must exactly match data
If you set an annotation to X Value = "2024-01" and your data uses "Jan 2024", the annotation will not appear — the block looks for an exact string match. Always check your axis label format and match the annotation value exactly.
⚠ Annotations are not supported on Bar, Line, Scatter, or Pie
The annotation (data callout) feature is only available on the Column chart type. For other chart types, use data labels for in-chart text, or place a text block overlaid on the chart canvas for manual annotations.