HTML - (Document) Outline (Table of Content)

This article talks:

• about the extraction of the outline
• from a HTML document
• in order to create a HTML Table of Content

The outline also known as the table of content is a list of one or more potentially nested sections.

The outline algorithm ¹⁾ extracts this information from:

• the loss heading (not inside section or hgroup)
• the section and:
  • its mandatory heading
  • and optional hgroup (to add a subheading)

You can check the outline with the w3 validator by checking the outline option.