Troubleshooting - Validation Target Size Test Result - User Verification

Issue

While the WCAG 2.2 Target Size Minimum requirement was written primarily for web content, it can also apply to interactive elements in PDFs. This is especially relevant when PDFs are viewed electronically and users interact with links and form fields using a mouse, touchscreen, stylus, or other pointing device.

Specifically the standard  requires that the target size for “pointer inputs” be at least 24 by 24 CSS pixels.  Unlike web pages, PDFs do not use CSS pixels but it can be approximately converted: 

• 24 CSS pixels ≈ 18 points (pt)
• 24 CSS pixels ≈ 0.25 inches
• 24 CSS pixels ≈ 6.35 mm

For PDF remediation purposes, many accessibility specialists use:  18 pt × 18 pt minimum target area  as the practical equivalent.

Some exceptions include:

• If “targets” are too small then they at least have to be spaced far enough apart.  
• PDF Links embedded in a paragraph or are surrounded by non-linked text.  

Symptom 

When running a WCAG 2.2 verification a PDF document with any links or forms, you will get a user verification for the target size minimum test.  The description is asking you to check and ensure that the target size of the link or form is not too small for users to select.

Cause

This test result will appear for every link and form in the PDF document.

Affected Users

The intent is to ensure, when viewed electronically, users with the following disabilties are able to interact with the links and forms using a mouse, touchscreen, stylus, or other pointing device.

• Tremors
• Limited dexterity
• Low vision
• Touch-screen devices

Accessibility Guidelines

WCAG 2.2, Success Criteria 2.5.8

Resolution Steps

When verifying a links and form fields in your PDF meet the minimum target size:   

•  Verify all form controls and link annotations have a reasonably large clickable area.
•  Use approximately 18 pt × 18 pt (24 × 24 CSS pixels) as the practical minimum target size.
•  Ensure checkboxes and radio buttons are not tiny.
•  Ensure the entire visible hyperlink text is clickable.
•  Check that adjacent interactive elements are not crowded together.
•  Remember that inline text links are often exempt under the WCAG exception.

If you need to make adjustments to the sizes of links and form fields, you will need to do that either in Adobe Acrobat Pro or in the source document and convert it back to PDF.

Verification

Once you have established that all your link and form targets meet the minimum requirement or are exempt from the requirements, you can change the results of these user verifications to passed.

Related Articles

This is even further explained in their article “Understanding SC 2.5.8: Target Size (Minimum) (Level AA).”  In that article, if you scroll down, you’ll find screenshots as they relate to not only the size requirement but also to spacing.  In fact, they include “passing” examples as well as “failing” examples.