Timeline

A Timeline is a saved, read-only visualization of temporal project data. It contains ordered series, optional nested groups, and relationship lines. It can show dates from fields or periods of snapshot validity. It does not schedule work or change dates by dragging bars.

The fictional Product Atlas fixture contains Aster Mini and Aster Pro under Products / Lumen devices, and Orbit Dock and Orbit Hub under Products / Orbit devices. Markets contains Northland, Westhaven, and Eastreach. Products have Release date, Support until, and Included features fields. The fixture has Planning, Launch, and Scale snapshots plus an inactive Concept branch; it has no Tasks Class or Due date field.

Permissions And Prerequisites

Project Viewers can inspect permitted calculated data. Project Analysts can create saved Views and change their own; Editors and higher can change other saved Project Views. A Layer-only user stays within permitted Layer data and does not gain unrestricted Project View authoring.

To change a source field, use authorized Details editing, generally Project Editor or a permitted Layer Editor for contextual data. The Timeline itself remains read-only regardless of your role. Linked occurrences keep their read-only Details context.

Set the Project timezone correctly before interpreting dates. Date fields are calendar dates in that timezone; Timestamp fields are rendered as instants in that timezone. The Timeline toolbar displays the calculation timezone. Changing your device's timezone is not a way to change the project's saved temporal data.

Choose A Time Source

Property time sources require Date or Timestamp value families. Text and Time-only fields are not compatible. Use single-value temporal fields for predictable scheduling data: the current picker also accepts multi-value Date/Timestamp families, but calculation reads only the first effective value, not one item per stored date. A field's name alone does not make it compatible.

Selecting Snapshot validity forces Resources item mode. A selected Start without an End family is explicitly Milestone (no end). If the selected Start value is unset but an End value is available, Resources mode can show that End as a milestone. Invalid temporal values or an End before Start are skipped with diagnostics; they are not silently swapped.

Create A Timeline

1. Open Product Atlas and show the View pane.
2. Choose Add view, enter Product release timeline, select Timeline, and create it.
3. Open the Timeline configurator if it is collapsed.
4. Choose Add series and label it Support windows.
5. Set Time source to Properties and Items to Resources.
6. Choose Release date for Start and Support until for End.
7. Select Lumen devices and Orbit devices in Resource roots with Children scope for each.
8. Choose a series color.
9. Set Granularity to Month and Visible range to Fit data. Use an as-of date in Scale, such as October 1, 2026.
10. Inspect the result and use Save view to persist the configuration.

Expected result: eligible product Values with valid effective dates appear as bars. An empty project or a series with no matching temporal data shows No temporal items, not an automatically generated schedule.

Creating another Timeline while a Timeline is active uses the current draft as a starting point. Creating it from another View type starts the Timeline defaults. Apply configuration changes and save the View before treating it as a reusable shared definition. View type is immutable after creation.

Series, Roots, And Filters

Each series has its own label, color, roots/scopes, item mode, time source, and local filter. Reorder series with their handles. Removing a series removes it from this View, not from the underlying products or tasks.

Resource scopes are Self, Children, Self or children, Descendants, and Self or descendants. Select a narrower root/scope to avoid including unrelated branches. Empty explicit roots use the default eligible roots rather than representing an explicitly empty candidate list.

The effective filter is:

active Layer AND Timeline page filter AND series filter

The active Layer is taken from the header and is not saved into the Timeline. Layer-only users cannot select All data. A contradictory filter combination can leave a series with no compatible contexts even when dates exist.

Use Conditions to understand the rule builder and Snapshots for effective period selection.

Worked Product Atlas Example

The unchanged fixture has these fictional field values in Launch and Scale:

1. Use the Support windows series described above.
2. Add a second series named Release milestones.
3. Choose Properties, Resources, Release date as Start, and Milestone (no end).
4. Select Lumen devices / Children and Orbit devices / Children.
5. Set a fixed visible range from January 1 through July 1, 2026.
6. Save the View.

Expected result: the four products appear as support bars with continuation beyond the visible range and as milestones on their Release dates. These dates are interpreted in the Project timezone. Selecting a milestone opens the relevant resource/field Details; it does not change Launch ready or modify the Release date.

To show Start and End as separate field milestones instead of a resource bar, change Items to Temporal properties on a property-based series.

Historical Evaluation

The Timeline is not merely a rendering of today's field values. It evaluates effective filters, dates, groups, and relationship references at historical snapshot segments. Boundaries elsewhere in the project matter too: a referenced market or task can change while a product's own snapshot remains unchanged.

Adjacent historical variants are coalesced only when their effective dates, context, grouping, and source match. A change of dates or context can produce separate items for the same resource. A snapshot applicability gap remains a gap, rather than carrying expired values forward.

Conditioned Launch Example

As an additional exercise beyond the fixture, keep Aster Pro's Scale Release date default at March 15, 2026, and add a Northland-conditioned Release date of October 15, 2026. Widen the visible range to include both dates.

Expected result: the Timeline can discover the Northland context from the conditioned temporal field itself, without requiring an identical Northland predicate to be repeated in the View filter. The global and Northland variants are not forced into one date. A Westhaven page/series filter is combined with that context and may exclude the incompatible Northland variant. Historical Launch-period evaluation retains the unmodified March date.

Inactive snapshots are not effective historical data. Where allowed tagged periods overlap, untagged effective periods take priority; otherwise the latest-starting tagged candidate wins, with a deterministic identifier tie-break. Tags do not create primary-tag timeline tracks.

Snapshot-Validity Series

1. Add a series named Product validity.
2. Choose Snapshot validity as Time source.
3. Select Lumen devices / Children and Orbit devices / Children. Items becomes Resources.
4. Choose a fixed range covering the periods you want to inspect.
5. Save and inspect the returned intervals.

Expected result: bars represent effective applicability intervals from Planning, Launch, and Scale, not an inventory of every stored inactive or losing tagged period. Concept branch supplies no bar because it is inactive. Open-ended intervals clip to the visible range and show continuation indicators. Use the snapshot editor for inspecting all authored periods; the Timeline is a calculated view of effective data.

The Timeline's As of date is independent of its visible range. It supplies the selected calculation date/fallback context; it does not collapse historical evaluation to one snapshot or automatically set the screen range to that date. The range controls what span the canvas presents. Details snapshot selection is independent of both.

Add Nested Groups

1. Drag a resource or property-family source into Nested groups.
2. Set the applicable resource selector scope where offered.
3. Add further group levels and reorder them using their handles.
4. Inspect the resulting nested rows and save the View.

Expected result: items are organized by effective context-aware resource/property bindings. An Alias in a data-definition drag resolves to its bound family. Families remain connected when their canonical label is renamed.

Multi-value property grouping can put the same temporal item into several rows. Several independent multi-value groups form Cartesian binding combinations. This is intentional grouping, not necessarily duplicate source records; use narrower groups if the resulting row expansion is excessive.

The current group drag editor accepts resources and property families. Do not assume every exact-occurrence type mentioned by internal evaluation types is a selectable grouping mode in this UI.

Relationship Lines

Choose reference families in Relationship lines to draw relationships between visible contextual items. Product Atlas's Included features connects products to Wireless sync, Compact chassis, Offline mode, and Extended battery. The initial fixture has no temporal fields on Features, so selecting Included features alone does not create feature endpoints or lines.

For an additional exercise, attach Release date to Wireless sync, set a valid date in its applicable snapshots, add a feature milestone series using Wireless sync / Self, and select Included features for Relationship lines. A product-to-feature line can appear when both visible items satisfy the historical/context checks below. This is extra authoring, not part of the seeded fixture.

Lines use effective historical references, not simply the current default reference set. Endpoints must share compatible Class context, and the target variant must be valid at the source evaluation instant. A line is absent when no eligible visible target variant exists.

The canvas renders lines for endpoints in the visible row window. Scroll to the relevant rows before concluding a relationship is missing. These lines visualize relationships; they do not enforce task dependencies, reschedule bars, or establish a critical path.

Navigate The Canvas

• Choose Day, Week, Month, Quarter, or Year granularity for the time ruler.
• Use Fit data for an automatically calculated range, or Fixed with an ordered start/end for a bounded comparison.
• Use Pan left, Pan right, Fit, Zoom in, and Zoom out for presentation.
• Scroll through virtualized rows and click a resource item or temporal field item to open its Details context.

Panning and zooming are navigation, not source-data edits. Continuation markers mean an interval extends beyond the shown range, not that its stored start/end was changed.

Troubleshooting And Limits

Current configuration limits are 24 series, 24 roots per series, eight nested group axes, and 12 relationship families. Context, candidate, item, relationship, and evaluation-work budgets also apply. Limits fail explicitly; do not interpret an error as a complete empty schedule.

Timeline bars and milestones are read-only. There is no drag-to-reschedule, dependency editing, project planning automation, critical-path calculation, or built-in export workflow in this surface. Date changes happen in Details and follow their own Undo support; saving a Timeline is a separate supported command, not reversal of every source edit.