Outlines and folding
Indented lines belong to the line above them, and the lines under a heading belong to that heading. Folding, zooming, moving and copying all follow that structure.
Indent
Tab indents the current line or selection under the line above it. ⇧TabShift+Tab moves it back out. Only the selected lines move, and the lines around them keep their indentation, so a line’s children stay where they are when you indent it.
To take the children along, press ⌘;Ctrl+;: it indents a line together with everything beneath it. ⌘⇧;Ctrl+Shift+; moves the whole tree back out. A folded line always takes its hidden lines along.
A line’s children come along when you move, fold or copy it.
The editor supports overindentation: you can press Tab multiple times to add more indentation.
Headings own their section
The lines below a heading belong to it until the next heading of the same or a higher level, with no indentation needed. Move or fold a heading and the whole section comes with it. Zoom into a heading and you see just that section.
Fold
Folding is what outliners call collapsing. ⌘/Ctrl+/ folds or unfolds the current line and its children. ⌘,Ctrl+, folds all children, ⌘.Ctrl+. unfolds them, and the line menu has the fold options too. Folding is per panel, so you can fold a page one way on the left and another way on the right.
Blocks, live queries and transclusions fold too.
Zoom
Zooming is what some outliners call hoisting or focusing in. ⌥↓Alt+Down zooms into the current line: that line becomes the top of the page, and the rest is hidden. ⌥↑Alt+Up zooms back out. The zoomed-in line stays visible and editable, so you can rename a heading while working inside it.
Move lines around
⌘⇧↑Ctrl+Shift+Up and ⌘⇧↓Ctrl+Shift+Down move a line past its siblings, children included. Drag a line by its handle to put it anywhere, in the same page or in another panel. To select a line with its children, press ⌘ACtrl+A until they are selected; see Selecting.
⌘ZCtrl+Z undoes any of it.