Accessibility checks for PDFs are organized into two categories: Failed Issues and Needs Manual Review.
This article focuses on the checks that can be evaluated on a pass/fail basis and are reported in the Failed Issues category.
Want to enable PDF checking on your site or account? Contact us via the in-app chat or email.
Checks Covered in this Article
The document must be correctly tagged.
The document must be correctly tagged.
Tagging a PDF means adding a hidden structure layer to the document, which allows assistive technologies like screen readers to understand and navigate the content. Tagged PDFs include elements like headings, lists, and images with alternative text, making them accessible to users with disabilities.
The results of this check are seen on both the PDF Listing Panel and the Failed Issues section of the PDF Detail View panel.
Learn about Common PDF Tags and Their Usage from Section508.gov.
Bookmarks should be created to assist with document navigation.
Bookmarks should be created to assist with document navigation.
PDF Bookmarks allow users to jump directly to different sections of a document. Users will find it difficult to navigate documents without bookmarks, especially if the documents are long or lack tags. Check only runs on PDFs of 9 or more pages.
If a document is flagged with this error, the reason will be: Document does not have bookmarks.
WCAG Correction Tips: Creating bookmarks in PDF Documents
Users should be notified when required form elements have not been completed.
Users should be notified when required form elements have not been completed.
Ensure users know if a required form field has not been completed, can determine what is wrong, and can correct it. Also, manually confirm that submitting the form with a required field blank shows an error.
WCAG Correction Tips: Indicating required form controls in PDF forms
Table elements must be used for table markup.
Table elements must be used for table markup.
Tables must be structured using table elements (Table, TR, TH, etc..) so the data relationships are clear, even if the table isn’t visible or the presentation format changes.
There are several reasons that can be returned when this issue is found:
Invalid child element of Table: (child name)
Invalid child element of Row: (child name)
Invalid child element of (element name): (child name)
(element name) element has no children
(element name) element has invalid child type: (child type)
WCAG Correction Tips: Using table element for table markup
Scanned images of text from hard copy documents should be converted into actual text.
Scanned images of text from hard copy documents should be converted into actual text.
Scanned pages that are only an image of text need a real text layer from OCR (Optical Character Recognition) so assistive technology can read the page. A text layer over a full-page image still needs review to confirm the text matches the image.
WCAG Correction Tips: Performing OCR on a scanned PDF document to provide actual text.
Headings should be tagged appropriately in the PDF tags tree.
Headings should be tagged appropriately in the PDF tags tree.
Heading elements should be used in the correct order to help users with screen readers navigate the document. Heading levels should not be skipped, as that can confuse users and make them think they have missed some content.
These flags can appear in both the Failed and Needs Manual Review categories.
Failed: Headings are in incorrect order - there is a jump from heading '(level A)' straight to heading '(level B).
Needs Manual Review: There was a problem with finding headings in the document. Please ensure that the headings are in the correct order.
This indicates that an error occurred while loading the headings.Needs Manual Review: There was a problem with iterating over headings on the page. Please ensure that the headings are in the correct order.
This indicates there was an error when processing the headings
WCAG Correction Tips: Marking Content with Heading Tags
Interactive form controls must be correctly labeled and usable by accessible technologies.
Interactive form controls must be correctly labeled and usable by accessible technologies.
Interactive forms should include clear, descriptive labels that are programmatically associated with their corresponding fields (using the tooltip entry /TU), ensuring assistive technologies can accurately identify and interpret them. Buttons may use the caption (/CA) entry. Confirm the visible label sits with the control.
WCAG Correction Tips: Providing labels for interactive form controls in PDF documents
Links and link text provided using the Link annotation and the /Link structure element to make them clickable.
Links and link text provided using the Link annotation and the /Link structure element to make them clickable.
The simplest way to provide links that comply with the WCAG success criteria is to create them when authoring the document, before conversion to PDF. If you don't have access to the source document for the PDF, you need to edit the link in PDF software. Link information should be programmatically available to user agents so that links are recognizable when presented in different formats. One way to do this is to ensure the links and link text use both the Link annotation and Link structure elements to make them clickable.
Reasons:
Link action is not defined.
Link rectangle is not defined.
Link action type is not defined.
Link URI is not defined
WCAG Correction Tips: Providing Links and Link Text using the Link annotation and the /Link structure element
Name, role, and value information should be provided for form fields.
Name, role, and value information should be provided for form fields.
Form fields need name, role, and value information so assistive technologies can gather their information and interact with them.
WCAG Correction Tips: Providing name, role, and value information for form fields
Text alternatives (Alt text) should be provided for non-decorative images using the Alt entry.
Text alternatives (Alt text) should be provided for non-decorative images using the Alt entry.
Images that convey relevant meaning or text to the PDF should have a text alternative entered using the /Alt entry in the property list for the tag. These /Alt entries are read to those using text-to-speech technology.
WCAG Correction Tips: Applying Text Alternatives to Images with the Alt entry in PDF files
The document title must be provided using the /Title entry in the document information dictionary.
The document title must be provided using the /Title entry in the document information dictionary.
A descriptive title for a PDF document must be specified for assistive technology by using the /Title entry in the document information dictionary. The DisplayDocTitle flag setting should also be set to True in a viewer preferences dictionary.
WCAG Correction Tips: Specifying the Document Title using the Title entry in a PDF document
Document must have correct tab and reading order.
Document must have correct tab and reading order.
If the tab order is not correct within a document, users that utilize assistive technology may not be able to understand the content.
This check can result in either a Failed or Needs Manual Review reason:
Failed: Tab order value is invalid. Users might not be able to tab through the page in the expected order. Tabs have not been set on the noted page(s).
Failed: Encountered an error when checking correct tab order. Please verify that the tab order is valid
Needs Manual Review: Tab order is set to (Structure, Row, or Column) order. Please ensure that tabbing through the document matches its logical order.
WCAG Correction Tips: Ensuring Correct Tab and Reading Order in PDFs
Verify that tables are correctly tagged.
Verify that tables are correctly tagged.
Table cells in PDF documents should be marked up to preserve and enable assistive technology to recognize the logical relationships among rows and columns. Verify that tables have correctly marked headers, rows, split, and merged table cells.
WCAG Correction Tips: Using Adobe Acrobat Pro's Table Editor to repair mistagged tables.
Verify that lists are correctly tagged.
Verify that lists are correctly tagged.
Lists must use list tags (L, LI, Lbl, and LBody) so assistive technology can tell list items apart from ordinary paragraphs.
WCAG Correction Tips: Using List tags for lists in PDF documents.
Related Articles
If you have questions, please reach out to our DubBot Support team via email at help@dubbot.com or via the blue chat bubble in the lower right corner of your screen. We are here to help!