Headings range from Heading 1 (H1) through Heading 6 (H6). Headings must be nested in order by their level; for example, H1 should precede H2, H2 should precede H3 and so on. Think of headings as signposts. Users navigating a PDF with a keyboard may tab through headings to get a sense of the document's structure and organization.
You must determine where headings belong in a document; Adobe cannot automatically detect where headings belong. Open the Reading Order tool in the Accessibility panel to add headings to a document. Use the cursor to draw a box around the content you wish to tag as a heading. Click the button for the appropriate heading in the Reading Order dialog box.
Heading elements can be converted to bookmarks to help users navigate the document.
WCAG requirement: 1.3.1 Info and Relationships