A sidebar represents a titled out-of-line element that is not a figure or something based on the <note> element.

A sidebar does not necessarily have a distinct point in the greater hierarchy—in many cases it can appear at any one of several locations depending on the output (e.g., at a typesetter's discretion).

Because a sidebar is a topic type, it can only come after another topic's title or (if present) body element. This means that if you need a sidebar to appear in your output in the middle of another topic, then you need to use the <d4pSidebarAnchor> element. That element allows authors to have sidebars appear in outputs at any arbitrary location without breaking the rules of DITA.

Sidebar topics may contain nested <subsection> topics.