<rsect [id=id]>reference section heading
. . . <rsub>reference subsection heading
The <rsect> element can be used to identify a reference section. It is useful to identify reference material that is presented in a series of similar sections. For example, each reference section could describe one software command.
An <rsect> consists of:
Optional introductory text
Optional reference subsections (<rsub>)
Each <rsect> section can have multiple <rsub> sections. Each <rsub> element must have a heading. A cross-reference to a reference subsection is not allowed.
The topic tree includes <rsect> headings but excludes <rsub> headings.
End tags (for either <rsect> or <rsub>) are not required.