# Tasks, Summaries, And Milestones
URL: https://pro.rv-grid.com/guides/gantt/concepts/tasks/
Source: src/content/docs/guides/gantt/concepts/tasks.mdx
Description: Task types and hierarchy behavior.
Task hierarchy is represented by `parentId`.

- `type: 'task'`: normal scheduled item.
- `type: 'summary'`: rollup row; dates and progress come from children.
- `type: 'milestone'`: zero duration (`startDate === endDate`, `duration: 0`).

Scheduling-relevant source fields include `taskMode`, `constraintType`, `constraintDate`, `deadlineDate`, `effortMode`, `workHours`, `percentDone`, `actualStartDate`, `actualFinishDate`, `remainingDurationDays`, `splitRanges`, `priority`, and `canLevel`.

Source row contract: `GanttTaskSourceRow` in `packages/enterprise/plugins/gantt/grid/gantt-plugin.types.ts`. Internal task entities use `manuallyScheduled`, `durationDays`, and `progressPercent` in `packages/enterprise/plugins/gantt/core/domain.ts`.
