Editing Outliner (section)

== Design ==
The principal attribute of outline editors is that they support or enforce the use of a [[hierarchy]] of their items. 
* Editing: Sound parent-child relationships are enforced when the user modifies the document structure. For example:
** Promoting, demoting, copying, or deleting a parent has the same effect on the children.
** Every item entry must be within one level of its predecessor, such that each item must be a sibling or child of the preceding item (thus, no item can be a grandchild of the preceding item).
* Viewing: The tool enables the user to affect the display by level. For example:
** Applying styles by outline level (e.g., bold all 1st level items).
** Displaying selected levels (e.g., show all 1st and 2nd level items, but none deeper).
** Lifting an entire section out to work on it in isolation, ignoring everything else during that editing, then dropping it back into place (known as hoisting and de-hoisting).
* Search/Filter: The tool displays only items that contain the query terms plus their ancestors (parent, grandparent...) to give them context.
* File import and export: Both the content and structure of outlines are conveyed when files are imported or exported (e.g., from and to tab-indented files).
* Fields/Columns: Items can also have additional fields of information. This data can be shown as columns of data in the outline or as fields in the second pane (see 'Layout' below). Some outliners also allow the user to create custom fields and/or filter on fields. It can be changed further.