Acrobat Chapter 1: Introduction

 Instructions

Section 1.1: What are Tags?

Tags are invisible markers that carry essential information about elements within a document. They are crucial for assistive technologies like screen readers, which rely on this information to interpret and convey the content. For instance, a screen reader needs to know whether an element is a paragraph, image, or a table. Screen readers cannot determine this unless the element is explicitly tagged.

Tags provide the semantic structure that describes the content and organization of a document. This structure is communicated to assistive technologies, which in turn make it accessible to users. When every element in a document has a clear semantic meaning, screen reader users can understand its organization and navigate it effectively.

For example, sighted users can visually scan a document and move from one heading to another, even if the headings are not correctly tagged. However, screen reader users depend on these headings being explicitly and semantically tagged to recognize them as such. Proper tagging allows screen reader users to easily jump from heading to heading.

Tagging a PDF is arguably the most critical step in ensuring its accessibility. If you are familiar with HTML, PDF tagging will feel familiar since the principles are similar. If you are new to this, a bit of practice will help you become comfortable with the process.

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:

  1. Optimize the original source document for accessibility.

  2. Convert the source document into a tagged PDF.

  3. Include metadata.

  4. Add or adjust tags as needed.

  5. Refine the reading order and tab order.

  6. Verify the accessibility of your work.

    The process to remediate a PDF when you start with the original source document.

If you need to work with a poorly tagged PDF:

  1. Add metadata.

  2. Create or refine the tags.

  3. Adjust the reading order and tab order.

  4. Check the accessibility of your work.

    The process to remediate a PDF when you start with a poorly tagged PDF.

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:

  1. Add metadata.

  2. For very simple documents, use Acrobat Pro to auto generate tags.

  3. For more complex documents, manually create the tags.

  4. Refine and adjust the tags as needed.

  5. Optimize the reading order and tab order.

  6. Evaluate the accessibility of your work.

If starting with a paper or scanned document:

  1. Scan the document, if needed.

  2. Use optical character recognition (OCR) to generate searchable text.

  3. Proceed with the steps for working with an untagged PDF.

Section 1.3: PDF Accessibility Standards

WCAG (Web Content Accessibility Guidelines) provides rules for making web content accessible. It includes 78 measurable criteria with clear pass/fail outcomes to help authors create accessible content. For example, text must meet a minimum color contrast ratio against its background. If it doesn’t, it fails that criterion. WCAG defines technical requirements (success criteria), techniques for achieving them, and additional guidance.

PDF/UA (PDF/Universal Accessibility), also known as ISO 14289, sets technical standards for accessible PDF documents, based on WCAG 2.0 principles. Like WCAG, it includes specific criteria for accessibility. Shortly after its release, the Matterhorn Protocol was created to help software developers, authors, and editors comply with PDF/UA. It lists 31 checkpoints and 136 failure conditions detailing how a document can fail PDF/UA standards.

Both WCAG and PDF/UA have significant overlap but serve slightly different purposes. Approved by the International Organization for Standardization (ISO), they share the common goal of creating an accessible user experience.

Yes, WCAG applies to PDFs, even though it only mentions them briefly:

"Some common examples of web content technologies include HTML, CSS, SVG, PNG, PDF, Flash, and JavaScript."

When you share a PDF on a website, it becomes web content, so WCAG standards apply. However, WCAG is primarily designed for websites, not documents. This can make it challenging for authors to interpret and apply these guidelines to PDFs.

The W3C Working Group has provided techniques for meeting WCAG using different technologies, including PDF. It's important to note that these techniques are informative. This means they offer guidance, but they are not normative. They do not establish mandatory requirements for WCAG compliance.

To learn more, visit the Techniques for WCAG 2.2.

Authors often find it challenging to navigate the overlapping requirements of WCAG and PDF/UA. To simplify this, a team of experts created a mapping of WCAG 2.0 guidelines to their corresponding PDF/UA standards. This effort resulted in a detailed guide called Achieving WCAG 2.0 with PDF/UA, published by AIIM (The Association for Information and Image Management), the ISO’s governing body. The guide provides clear steps for achieving WCAG 2.0 compliance using PDF/UA. However, it only covers WCAG 2.0 and does not include the 17 new success criteria introduced in WCAG 2.1.

WCAG and PDF/UA work well together, and using both ensures the creation of highly accessible PDF documents.

This course will focus on WCAG compliance.

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