Accessibility in PDFs
Movement through a web page or application should follow a logical order that matches the visual order of content on the page.
For most documents, screen readers read from left to right and top to bottom. When creating documents, be aware of this and author content accordingly. For documents that contain content in multiple columns, be sure to test with a screen reader. If you’re unsure how to do this, UW-IT Accessible Technology Services will be happy to do this for you.
PDF files present unique challenges since they are generated from other software products that may not export content in a logical order for reading. Techniques for testing and, if necessary fixing, the read order in PDFs depends on whether the PDF is a document or form.
Techniques for PDF documents
Usually when people talk of a PDF file being accessible it is a ‘tagged’ document. A ‘tag’ in a PDF is similar to a HyperText Markup Language (HTML) tag. Basically it is part of the coding of the document that Assistive Technologies (AT) can recognize, and provide a way for the AT to navigate the document. Preferably tags are assigned in a document when creating a PDF using Adobe’s Acrobat software. This document will show how to create an accessible PDF file without access to Adobe Acrobat software, by simply using Microsoft Word. Without Adobe Acrobat, the easiest way to create an accessible PDF file is to first begin with an accessible Microsoft Word document.
Step One: Create an Accessible Word Document following these steps:
1. Use Appropriate Font Style and Size - Not all fonts are created equal when it comes to accessibility. The font styles listed below are the most commonly recommended due to both their readability and availability across a variety of computer operating systems. Generally, sans serif fonts work best as screens with low resolution make serif fonts more difficult to discern. In order to ensure that documents will be accessible to the largest audience possible, choose one of the following sans serif font styles: Arial Verdana with a minimum standard font size of 12 point.
2. Use Color Appropriately Good Contrast- People who have low-vision or color-blindness have difficulty reading documents when text color does not strongly contrast with the background color. Problems with colored text also arise when printing on a black and white printer. Not having enough contrast between the foreground and background colors may make the words difficult to read. When producing documents ensure that the text and background have a sufficiently high level of contrast. Documents with low contrast can be difficult, if not impossible to read for people with low vision. It is sometimes difficult just by looking at a document to tell exactly the ratio of contrast. Also, follow this important rule: Never use color alone to convey important information.
3. Add Alternative Texts and Captions- Many images, graphics or tables included in documents need to have alternative text and captions. Otherwise these items will not be perceived, nor properly understood by persons who have visual disabilities. Alternative text and captions are read by screen readers allowing the content and function of these images, graphics or tables to be accessible to those with visual or certain cognitive disabilities. Wrapping Text- Lastly, when adding an image or graphic always set the wrapping style to In Line with Text. Text that wraps around an image or graphic often times will confuse a screen reader, making it difficult for the user to understand.
4. Specify Column Header Rows in Tables- Microsoft Word provides an easy method for creating accessible simple tables. If more complex tables are used it is recommended that a description or explanation of the table contents be included in the text of the document. A Header Row needs to be identified to allow the heading text to be distinguished from the data area of the table. Always try to construct simple tables
- Only use one row in the Header.
- Never Merge or Split cells.
- Try not to leave any cells, rows or columns Blank.
5. Use Meaningful Hyperlink Text- Hyperlink text should provide a clear description of the link destination. One of the ways a person who uses Assistive Technologies can navigate a document is by skipping from hyperlink to hyperlink, or they can also pull up a list of all the links in a document (Insert + F7). Since both of these methods of navigation do not include any of the surrounding text, the hyperlink text by itself needs to provide sufficient meaning. For this reason, using phrases like, Click Here, or Visit are not sufficient as they by themselves do not provide enough meaning.
6. Use Built-in Formatting Styles- Using built-in formatting styles could be the single most important step in making documents accessible. Built-in formatting styles provide a logical reading order that serves as a navigation guide for persons utilizing assistive technologies. Always use styles to format documents. Most importantly, always use styles to create Headings and Lists.
Apply Heading Levels in Style Formatting- When headings are defined using Word's built-in heading styles, Screen Reader users can quickly navigate through the document and can easily skip from heading to heading. When headings are incorrectly marked up, using character formatting only (e.g., applying BOLD format, and/or using ALL CAPITAL LETTERS), there is no programmatic way for the Screen Reader to know where the headings are in the document.
Heading Order- Assigning headings in documents is the most important accessibility feature that can be added to a document. Traveling from heading to heading is the number one way people who use Assistive Technologies navigate documents. Headings should be applied to provide a sequential and relational understanding. This means that the heading which introduces a big idea, should be identified as a Heading 1 (read by a screen reader as, Heading, Level 1). If the next heading still speaks to some aspect of the same idea introduced in your Heading 1, then it should be identified as a Heading 2 (read as, Heading, Level 2). The next heading could be another Heading, Level 2, a Heading Level 3, or if a new big idea is being introduced a Heading, Level 1. Other rules for Headings:
- Sequential headings should never be more than one level apart from one another. Meaning, you can follow a Heading 2 with either a Heading 1 or a Heading 3, but not a Heading 4.
- The first Heading in a document should be assigned as a Heading 1.
- You may have multiple Heading 2s after a Heading 1. This same rule applies to all Heading levels.
- In Word you may assign heading levels down to Heading 9.
Table of Contents- In addition to providing a quick and necessary way for persons using Assistive Technologies to navigate a document, applying Headings has another excellent benefit for content creators and document reviewers. A Table of Contents can be added to a document in four easy steps. 1. Place cursor at the desired Table of Contents location 2. Go to References tab 3. Click on Table of Contents 4. Choose a style and click To navigate by Keyboard, Alt, S, T 13 The Table of Contents will include all Headings, show their relationship to each other, and they will automatically be hyperlinks.
List Formatting- When bulleted or numbered list formatting is used, screen readers will properly announce the text as being part of a list. List formatting provides the user with a means to quickly navigate between items as well as move in and out of lists. When lists are made with repeated use of the Tab key or Spacebar, screen readers will not recognize them as lists, meaning that the list reading controls are inoperative. Set lists in Word by: Home Tab, Paragraph Group and use the list controls. Navigating by Keyboard - make a list by first highlighting the text then pressing Alt, H, then U for Unordered list (bulleted list), N for Numbered list, or M for more options for the list. To indent - Alt, H, then AI for increasing indent, or AO for reducing indent.
7. Check Accessibility- Perform a test of the document’s accessibility prior to distributing it either via email or by posting it to the internet. Use a screen reader such as JAWS, NVDA, Window-Eyes, etc. Preferably, develop an Accessibility Testing team of persons experienced at using Assistive Technologies. Microsoft Word 2010 also has a built-in accessibility feature. However, do not rely on machine testing alone to test for accessibility. To access the Accessibility Checker in Microsoft Word 2010: In the File tab, click on Info, Check for Issues, and then Check Accessibility. If navigating by Keyboard - Alt, F, I, I