Chapter: Indicates the start of a new topic with a new title.
<chapter id=id>title topic text ...
An end tag is not required.
If the topic title is long, you may want to provide an alternate abbreviated title using <abbrev>. The short title is used in the Index and History dialog boxes. If the title contains a graphical element, create an <abbrev> with the title text only.
Here are two markups that begin a new topic:
<chapter>A Manual of Style <chapter id=DesktopTools>Desktop Tools