Acrobat Chapter 1: Introduction
- Daniel LaGrow
Instructions
Section 1.1: What are Tags?
Tags are invisible labels that help identify document elements, making them essential for assistive technologies like screen readers. These tools rely on tags to determine if an element is text, an image, or a table. Without tagging, screen readers can't interpret the document's structure.
Tags provide semantic organization, allowing screen readers to convey the document’s layout to users. Sighted users can visually scan headings, but screen reader users need properly tagged headings to navigate efficiently.
Tagging a PDF is crucial for accessibility. If you know HTML, PDF tagging will be familiar; if not, some practice will help you understand it.
Types of Tags in Acrobat:
Article
Annotation
Bibliography
Block Quote
Caption
Code
Division
Document
Figure
Form
Formula
Heading
Heading Level 1-6
Index
Label
Link
List
List Item
List Item Body
Note
Paragraph
Part
Quote
Reference
Section
Span
Table
Table Data Cell
Table Header Cell
Table of Contents
Table of Contents Item
Table Row
Section 1.2: Remediation Flow in PDF Documents
If you have the original source document:
Optimize the original source document for accessibility.
Convert the source document into a tagged PDF.
Include metadata.
Add or adjust tags as needed.
Refine the reading order and tab order.
Verify the accessibility of your work.
If you need to work with a poorly tagged PDF:
Add metadata.
Create or refine the tags.
Adjust the reading order and tab order.
Check the accessibility of your work.
If the tags are in very bad shape, you might find it easier simply to delete them all and start tagging from scratch.
If you need to start with an untagged PDF:
Add metadata.
For very simple documents, use Acrobat Pro to auto generate tags.
For more complex documents, manually create the tags.
Refine and adjust the tags as needed.
Optimize the reading order and tab order.
Evaluate the accessibility of your work.
If starting with a paper or scanned document:
Scan the document, if needed.
Use optical character recognition (OCR) to generate searchable text.
Proceed with the steps for working with an untagged PDF.
Section 1.3: PDF Accessibility Standards
WCAG (Web Content Accessibility Guidelines) provide rules for making web content accessible. They include 78 clear, measurable criteria with pass/fail standards. For example, text must have a minimum color contrast against the background—if it’s too low, it fails. WCAG defines technical requirements (success criteria), methods to meet them, and additional guidance.
PDF/UA (PDF/Universal Accessibility) is the standard for making PDFs accessible, also known as ISO 14289. Based on WCAG 2.0, it sets specific criteria for accessibility. To support this, the Matterhorn Protocol was created, outlining 31 checkpoints with 136 failure conditions to help developers and document authors follow PDF/UA.
WCAG and PDF/UA are similar, with some differences, but both aim to ensure an accessible user experience. Both are published by the International Organization for Standardization (ISO).