Working with outlines is often a matter of locating ideas and restructuring them. The simple operation is to select a single header and move it in some way. But novice outline users quickly outgrow that limitation and want to move many headers. Some outliners allow you to select a header and promote not just it, but it and all its children as well. A much more powerful selection method is the “search” command. For instance: “select all headers containing the word ‘example’ and created or modified in the last 10 days, together with their children.” You can then drag that discontinuous assembly to a new header location and it will create a new branch of all those parts based on certain rules.
Tinderbox is the only outliner that fully supports this, and can gather to a clone. MORE developed it in that powerful context. Tinderbox’s implementation is automated, where MORE’s involved a manual search. No other outliner seems to have anything close. Some outliners can gather by sorting on pretagged characteristics. The screenshot shows one of these: Liner.
NoteBook takes a different tack. It automatically gathers by the tags you apply and can do custom “gathers” of multiple tags. These are collected on index pages from whence you can copy and collect on regular pages.