Set Annotation Contents: Add Alternate Description to PDF Annotations

Creating an accessible PDF isn’t just about tagging text — it’s also about making sure every annotation, from highlights to form fields, has meaningful, screen-reader-friendly descriptions. Without these descriptions, assistive technologies may ignore or misinterpret important document features, leaving accessibility gaps and risking non-compliance with standards like PDF/UA and WCAG.

With PDFix Desktop’s Set Annotation Contents feature, you can easily add or update alternative text for annotations, ensuring that blind and visually impaired users receive the same contextual information as sighted readers — while keeping your documents compliant with industry accessibility standards.

The Set Annotation Contents action in PDFix Desktop lets you define or update the descriptive text associated with a PDF annotation’s Contents key (for most annotation types) or TU key (for form field widgets). This text is what assistive technologies like screen readers use to describe an annotation’s purpose or function.

By using this feature, you can:

• Add custom alternative text (e.g., “Go to Page 3”, “Decorative”, “Click to Submit”)
• Extract visible text inside a highlight or annotation bounding box
• Describe interactive elements such as links, form fields, and buttons
• Automatically generate content based on document context or annotation actions (e.g., URI or page destinations)

By ensuring annotations are described accurately, you close accessibility gaps, improve navigation for assistive technology users, and meet key compliance requirements without tedious manual editing.

• Review all configurable parameters to understand which ones can be adjusted for your use case
• Use "Text from annotation bounding box" when the annotation visually highlights clear text (e.g., Link, Underline, Highlight)
• Use "Action destination" for Link annotations to describe where the link leads (e.g. “Go to Page 4” or “Open external URL”)
• Widget (form field) – Set TU key using custom or layout-based content
• Use "Custom text" (e.g. "Decorative") to mark visual annotations that are non-semantic
• Always enable the Overwrite when cleaning old or non-compliant annotations

Compared to traditional tools, PDFix Desktop allows precise and repeatable annotation tagging.

• Integrated with visual layout analysis for smart content extraction
• Supports batch tagging and template-based workflows
• Editable JSON configurations for automated accessibility pipelines
• Complies with latest accessibility standards (PDF/UA, WCAG)

This article was prepared by the PDFix Team, leveraging extensive experience in PDF accessibility, document automation, and compliance technology for over 20 years. PDFix is trusted by document professionals worldwide for robust, SDK-driven PDF workflows.

Have questions or need help with accessibility tagging?
Contact us at support@pdfix.net.