Use a sidebar for ancillary content that doesn’t fit into the flow of the document’s narrative. A sidebar can be titled and contain any type of content such as source code and images.

Sidebar syntax
.AsciiDoc history (1)
**** (2)
AsciiDoc was first released in Nov 2002 by Stuart Rackham.
It was designed from the start to be a shorthand syntax
for producing professional documents like DocBook and LaTeX.
****
1 A title is optional.
2 A sidebar is delimited by four asterisks (****).
Result: Sidebar with title
AsciiDoc history

AsciiDoc was first released in Nov 2002 by Stuart Rackham. It was designed from the start to be a shorthand syntax for producing professional documents like DocBook and LaTeX.