Annotation

An annotation is an interactive element positioned on top of a PDF page rather than being part of the page's drawn content: a link, a form field, a comment or sticky note, a stamp, or an embedded media player.

Annotations are separate from the structure tree, and that separation is the source of most of their accessibility problems. A link, for example, is really two things - the visible blue underlined text drawn on the page, and an invisible clickable rectangle placed over it. If the two are not joined up in the tags, a screen reader can announce a link with no text, or read text that never reveals it is a link. The same applies to form fields, which need their own labels because there is no drawn text a reader can borrow.

Because annotations are also what a keyboard user navigates between, a page containing them needs to declare the order in which they should be reached.

Learn more

• Tagged PDF Best Practice Guide: Syntax - the PDF Association's guidance on tagging annotations
• Structure tree
• Keyboard focus