Two conditions must be met to make a PDF document accessible:
- The metadata must be correct and complete.
- The document must be fully tagged.
Tagging a PDF document with metadata means that each content element (e.g. title, numbered lists, images, ...) is assigned a specific tag type, which is inserted at the right place in the structure (also called "tag tree"). The tag type determines the type of element (e.g. an image), while the tag tree determines the sequence in which the text components are read.