Summaries
Summaries automatically calculate the values of parent rows in the selected column. Leaf rows (rows with no children) will be editable as normal, but any row with descendants will have its value calculated based on the descendants. For example, if you have a number column with a Total summary enabled, parents' values will be the sum of their children's values, like the screenshot shown here.
Summaries can be set up using the Column Type inspector or the contextual menu. Only summaries that are supported by the current column type will be available; make sure you set the column type before setting the summary type.
None
No summaries are applied to the column and all values can be edited normally. This is the default setting for new columns.
Hidden
Parent rows' values will not be shown in the outline. The values still exist, so if you turn off Hidden summaries, you will see them again.
Total
Each parent row's value will be a sum of all of its children's values.
Minimum
Each parent row's value will be equal to the lowest value among its children. For pop-up list columns, items toward the beginning of the list are considered "lower".
Maximum
Each parent row's value will be equal to the highest value among its children. For pop-up list columns, items toward the end of the list are considered "higher".
Average Leaves
"Leaves" are rows with no children, just like the leaves of a tree are at the end of its branches. With this summary selected, each parent's value will be the sum of all descendant leaves' values, divided by the number of descendant leaves. Keep in mind that this summary pays attention to all descendant leaves, not just immediate children, and that it ignores rows with children of their own.
State
This summary is specific to the checkbox column type. If all children's checkboxes are checked, the parent's will be checked. If all children's checkboxes are unchecked, the parent's will be unchecked. If some children's checkboxes are checked and some are unchecked, the parent's will be in an indeterminate state.
