Some text content can be marked with a circle and a number inside and be linked to its description in the document.
The content to be described is presented by the co element. The co element must be integrated into one of the following:
literallayout,
programlisting,
classsynopsisinfo,
computeroutput,
funcsynopsisinfo,
prompt,
replaceable,
screen,
synopsis,
systemitem,
userinput.
The majority of these elements are used to reproduce the computer (programming) environment. The literallayout has the semantics closest to the element simpara (simple paragraphe) most often used for text blocks. This element will be used below for the configuration of cos.
The description is wrapped in the element calloutlist made up of the callout elements.
In Document, insert the literallayout via the menu → . Write text for the item you want to describe.
With the menu → , insert an element co inside the element literallayout.
Repeat steps 1 and 2 for all the elements you want to describe.
Give each co element an ID.

Add the calloutlist element via the menu → .
Add as many callout elements that there are elements to describe with the menu → .
Give each callout an ID.
Create a link between each callout and its respective co by placing:
the identifier of the co in the arearefs attribute of the callout:

the identifier of the callout in the linkends attribute of the co.

Publish the document.

By default, the dots are black circles with white numbers. Any change to the default rendering represents further expansion of the style sheet.