> ## Documentation Index
> Fetch the complete documentation index at: https://learn.nextedy.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Baselines Parameters
> Nextedy GANTT supports baseline comparison to visualize the difference between the current schedule and a historical schedule snapshot.
export const LastReviewed = ({date}) => {
if (!date) return null;
const formatted = new Date(`${date}T00:00:00Z`).toLocaleDateString("en-US", {
year: "numeric",
month: "long",
day: "numeric",
timeZone: "UTC"
});
return
Last reviewed on {formatted}
;
};
## Baselines Widget Parameters
| Name | Type | Default | Description |
| ----------------- | ------- | ------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `Show Baselines` | Boolean | `false` | When enabled, the Gantt automatically loads and displays baseline data on every page load using the configured `Compare to date` value. |
| `Compare to date` | String | Empty | The default comparison reference point. Accepts a relative date (T-minus), a specific date, or a page parameter reference. Only visible when `Show Baselines` is `true`. |
The `Compare to date` parameter only appears in the widget parameter editor after you set **Show Baselines** to `Yes`.
## Comparison Modes
The Gantt supports three methods for comparing the current schedule against a historical snapshot:
| Mode | Description | Available Since |
| -------------- | --------------------------------------------------------------------------------------------------------- | --------------- |
| Specific date | Select a calendar date to compare against. The Gantt loads task positions as of that date. | Version 1.5 |
| Named baseline | Select a named Polarion baseline from a dropdown. The baseline revision provides the historical snapshot. | Version 2.4.0 |
| SVN revision | Enter a specific SVN revision number. The system validates the revision exists before applying. | Version 25.3.0 |
## Automatic vs. One-Time Comparison
**Automatic comparison** (`Show Baselines` = `Yes`): The Gantt loads baseline data on every page render using the `Compare to date` value. Baseline bars are always visible.
**One-time comparison** (toolbar button): Click the **Compare with History** toolbar button to open a dialog where you select the comparison mode and reference point. The comparison persists until you close it or navigate away.
When `Show Baselines` is configured but the user triggers a one-time comparison with a different date, the one-time comparison takes precedence and refreshes the baseline display.
## Compare to Date Formats
The `Compare to date` widget parameter accepts the following formats:
| Format | Example | Description |
| ------------------ | ------------ | --------------------------------------------------------------------------------- |
| Relative (T-minus) | `T-30` | Compare against the schedule 30 days ago. |
| Specific date | `2024-01-15` | Compare against a fixed historical date. |
| Page parameter | `$pageParam` | Use a Polarion page parameter value, allowing users to pick the date dynamically. |
## NEW Badge for Added Tasks
Since version **25.3.0**, tasks created after the selected comparison point are marked with a **NEW** badge. This helps you identify work items that were added to the schedule after the baseline was taken.
## Baseline Data Fields
When baseline comparison is active, the Gantt data response includes two additional fields per task:
| Field | Type | Description |
| -------------------- | ------ | --------------------------------------------------------------------- |
| `planned_start_date` | Date | The start date of the task as of the comparison date. |
| `planned_duration` | Number | The duration (in working days) of the task as of the comparison date. |
These fields drive the secondary baseline bar rendered below each current task bar.
## Baseline API
Named baselines are fetched from the Polarion server via the baselines API endpoint. Each baseline record contains:
| Field | Type | Description |
| ------------ | ------ | ----------------------------------------------------- |
| `revisionId` | String | The SVN revision number associated with the baseline. |
| `name` | String | The user-defined name of the baseline. |
| `created` | Date | The creation timestamp of the baseline. |
## Pre-Conditions
* **Unsaved changes:** The Compare with History dialog cannot be opened when the Gantt has unsaved edits. Save or discard changes before comparing.
* **Read-only mode:** Baseline comparison is fully available in read-only mode.
## Item Script Approach
For item-specific baselines (instead of a single historical date), use the [Item Script API](/gantt/reference/api/item-script-api) to set planned dates per item:
```javascript theme={null}
task.planned_start_date = util.getDate(wi, "gantt_initial_start");
task.planned_duration = util.getDuration(wi, "gantt_initial_duration");
```
This compares each item against its own saved initial schedule rather than a single global date.
## Configuration Example
To show automatic baseline comparison against a date 30 days ago:
1. Open **Widget Properties** for the Gantt widget.
2. In the **Baselines** section:
* Set **Show Baselines** to `Yes`.
* Set **Compare to date** to `T-30`.
3. Save the widget parameters.
The Gantt chart now displays baseline bars on every load, comparing the current schedule against the state 30 days prior.
## Related Pages
* [Work Items Gantt Widget Parameters](/gantt/reference/widget-parameters/work-items-gantt) -- main widget parameters
* [Item Script API](/gantt/reference/api/item-script-api) -- per-item baseline scripting
* [Toolbar Actions and Keyboard Shortcuts](/gantt/reference/keyboard-shortcuts) -- Compare with History toolbar button