To open the "Editing Task" window, double-click the task name cell or click the "Edit Task" button on the "Gantt Chart" ribbon.

Task Detail Window

MilestoneIf a task is a milestone, the duration is always 1.
WBSIn terms of project management, the work breakdown structure (WBS) is a hierarchical breakdown of a project’s deliverables or phases. Gantt Chart Maker for Excel manages this field automatically. You use the "Make Parent", "Make Child", "Move Up", and "Move Down" buttons on the ribbon to change the WBS of a task.
% CompleteThis is the percentage complete for the task. It is an integer between 1 and 100. If it is set to be calculated automatically, this percentage will equal "actual duration / estimated duration".
CategoryIf you choose a category, the task line will be marked with a special background. To define the list of available categories, use the "Category" button in the "Settings" group of the Excel ribbon.

It could be people's (the task owner's) names or other resources like rooms, machinery, etc. For each resource, you can set rest days and holidays. These days will be used when calculating task durations and dates. To set the list of available resources, use the "Resources" button in the "Settings" group of the Excel ribbon.

If the resource field is left blank, multiple resources are assigned, or an invalid resource (a resource that couldn’t be found in the "Resources" table) is assigned, then the "<Default>" resource will be used on calculations.

Dates and durations

There are three types of dates and durations: Estimated, baseline, and actual.

The estimated dates are the main ones, which map to the "Start", "End", and "Duration" columns on the task list of the Gantt sheet. The app draws a full-sized shape according to the cell sizes to represent the estimated start date and end date.

Baseline dates: Use this as a snapshot of the estimated dates when a task is created. This gives you an easy way to find out how a task was originally planned.

Actual dates: When the task is done.

Both the baseline and actual dates are optional. If they are filled, the app draws smaller shapes over the estimated shapes.

If the task is a parent task, its estimated dates are automatically calculated from its child tasks; baseline dates and actual dates could be set to auto-calculated or manually entered. The duration of a parent task could be either the sum of the durations of the child tasks or the difference between the start date and the end date. All these options could be set by clicking the "Project Options" button on the Excel ribbon.

If a parent task has multiple child tasks, the start date of the parent task is the earliest start date of all the child tasks, and the end date of the parent task is the latest end date of all the child tasks.