Accessible PDF Guidelines and Standards.
Minimum Required Software.
Acrobat 5.0 with Make Accessible Plug-In installed (this plug-in is automatically installed with Acrobat 5.05 and higher).
It is strongly recommended that you design for accessibility as much as possible in your documents and select publishing tools that support accessibility features.
While there are tools that allow you to modify a Tagged (accessible) PDF structure, they are currently time-consuming to use. Fixing a document’s Tagged PDF can take anywhere from half an hour to an entire day, depending on the magnitude of accessibility problems that are found. In addition, it is not possible to save and reapply your fixes to a document’s Tagged PDF on the next revision of the document. For example, you put in 4 hours of work fixing the Tagged PDF structure of a document. Three months later, you finish an update to that same document. You will have to redo the fixes on the revised document. Your goal is to minimize the amount of post-PDF processing that you need to do on each document.
Adobe Acrobat 5.0 and later has built-in support for documents created in Adobe FrameMaker, Adobe InDesign, and Microsoft Office 2000 and later. Using one of these software titles to create your document and properly preparing the document, as described below, will greatly reduce the time and effort it will take for you to insure full accessibility of the PDF version of your document. In particular, Microsoft Word 2000+ offers advanced integration with Adobe Acrobat 5.0+. Using unsupported word processing programs, like WordPerfect, Lotus 1-2-3, and others may increase the time you spend to add accessibility features after conversion by many, many hours – estimated at as few as 5 hours for simple documents to as many as 30 or more hours for complex documents.
Accessibility can be a relatively easy, low-effort addition to the documentation production process. Yet, for PDF, this can only be true provided that you consider accessibility during the document design phase. Much of the work in creating an accessible PDF document happens in the creation of the document itself, not in the conversion to PDF.
Users who intend to publish a document in PDF should prepare for conversion by:
Before considering how to prepare or retrofit a PDF document for accessibility, you must understand the issues within a non- or semi-accessible PDF document.
Three levels of PDF Accessibility.
Creating a tagged PDF document will resolve a majority of the accessibility issues with PDFs, and, for complex documents containing columns and extensive data tables, may offer the only method for meeting accessibility standards. Tagged PDF represents various components of a document, such as chapters, heading styles, blocks of text, tables, graphics, and so on, as tag elements.
The tag structure is similar to markup languages such as HTML and XML. A document’s structure is represented as a hierarchy of tag elements. The order in the hierarchy represents the reading order of the document. Since the content is represented with tag elements, other applications can extract the information and reuse it for other purposes. Tagged PDF offers the following benefits:
The following is a summary of the necessary elements for an accessible PDF document. Included are suggested workarounds for structured and tagged PDFs (see "Three Levels of PDF Accessibility"), as well as methods for checking the accessibility of your existing PDF documents using Adobe Acrobat Reader 6.0.
A fully accessible PDF will address or provide workarounds for these issues:
Encoding the proper, or logical, reading order for a document is one of the most fundamental steps towards accessibility. This is especially critical for documents with columnated formats or where there are several distinct text blocks. For example, if a document has been correctly authored using two columns to create a two-column format, the screen reader knows it should read all the way down the first column and then proceed to the second column. On the other hand, if the writer used tabs to imitate the look of two-column text, the screen reader would not recognize the layout as two-column. Instead, it would simply read horizontally, going from the first line in the first column and then tabbing over to the first line in the second column. To insure that your graphics retain their proper reading order, you must also make sure that the graphic has been inserted inline with the text.
Structured PDF – text is presented in single
User Checks for Read Order:
Ability to reformat, or reflow, document content. Magnifying the font size is not a viable solution since the viewer must scroll widely in all directions to cover the document. Instead, an application should reflow the magnified text into the available screen space such that the text reformats itself to conform to that space. Text reflow is also used, for example, to reformat a document for display on a Palm Pilot, although that is not a primary concern for accessibility. Text reflow is a good example of a feature that benefits users who do not have disabilities.
Structured PDF and Tagged PDF – use only TrueType fonts and all scanned or imaged text has been converted via “OCR”, so it is selectable and sizable.
User Check for Reflow:
Zoom or enlarge the document view to 300% or more. From the VIEW menu, choose REFLOW. Does the text rearrange to fit within the available screen window? If you still have to scroll left-right or if the text appears distorted, the document does not reflow.
Include alternative, descriptive, text for all images. For example, in Acrobat, you can use the Tags palette to add a description of an image. Then, when a screen reader encounters that image in the document, it will read the alternate text description so the user can understand what the image is about.
You should seriously evaluate the information that a visual is conveying. Is the information already present in the text? Is the visual simply providing color and images that are not essential to the message conveyed by the document? The alternate text that you tie to a visual should not repeat the caption.
Structured PDF – include descriptions of all images
in the body of the text. Example: “Image 5.1 depicts a young boy on
User check for ALT-text for images:
Since only a screen reader can detect ALT tags, you need to either examine the "TAGS" screen for the document, or, if you are unsure if ALT tags exist for the document, add captions within the body of the text (preferably before the image) that describe the images.
add descriptive text for data tables. Do not “nest” data tables by putting one table inside another. Use a distinctive cell for each data entry.
Structured PDF – add descriptive text
[caption] within the body of the text either immediately above or below
User checks for accessible data tables:
A screen reader is usually required to test for the accessibility of tables. If you are unsure of how the table was created, add a description in the body of the text (preferably before the table) that explains the information conveyed in the table. If this is not possible, you may need to recheck/recreate the document in it's originating software. You may also check for accessibility by viewing the document tags in a full copy of Acrobat (VIEW --> NAVIGATION TABS --> TAGS).
A document's security settings will make it inaccessible to screen readers if it’s an Acrobat 4.0-compatible document and copying text and graphics is prohibited, or if it’s an Acrobat 5.0-compatible document and accessibility is prohibited. If you must protect the content of the document, offer it in a password protected site or in alternate format by request.
User checks for document security:
To view the current document security settings, open the FILE menu, choose DOCUMENT PROPERTIES, and then select SECURITY from the left menu.
Although not required to make a PDF accessible, the following additions to your PDF will significantly increase the usability of the document for users of assistive technology.
Because of the lack of universal support for Adobe products, users of screen readers often have fewer options for moving through a document. Especially in longer documents, like dissertations and research reports, in-document links can facilitate getting to particular portions of the document quickly.
Minimum standard: set PDF conversion settings so that each header tag is also converted into a bookmark.
Best practice (in addition to the minimum standard):
Note: For documents created in supported software with correct conversion settings, heading bookmarks will match the entries for table of contents, unless style sheets were not used properly to identify the start of each chapter/section. However, adding in-document links in the form of a table of contents allows the user to jump to various sections of the document without moving between the bookmark and document windows in Adobe Acrobat Reader.
Although current screen readers are designed to read the document according to one particular language, specifying the language of the document in the structure can benefit future screen reader technologies that may be able to change languages on the fly.
After creating your PDF document, Acrobat provides a tool called the Accessibility Checker to check various aspects of accessibility for a document.
Tip: if you turn on the “comment creation” before running the checker, you can page through the document and note where the Accessibility Checker has flagged problems in the document.
Step One: Before Converting to PDF
Insure that the originating software supports creating “Tagged PDF” or follow the guidelines for creating “Structured PDF” (see "Three Levels of PDF Accessibility").
Follow the guidelines for best conversion outlined in this guide:
Step Two: During Conversion to PDF
Step Three: After Converting to PDF
Use Adobe’s “Accessibility Checker” to identify and repair any unresolved accessibility issues: After creating your PDF document, Acrobat provides a tool called the Accessibility Checker to check various aspects of accessibility for a document.
Tip: if you turn on the “comment creation” before running
the checker, you can page through the document and note where the
Accessibility Checker has flagged problems in the document.
PDF and OSU Standards.
As a companion to this guide, the WAC also offers "Accessibility and PDF Documents" a guide to implementing PDF document distribution in compliance with the OSU Web Accessibility Policy and Standards.
Training Video Online.
The National Center on Accessible Information Technology in Education (AccessIT) at the University of Washington serves to increase the access of individuals with disabilities to information technology in educational institutions at all academic levels nationwide. The WAC recommends the very helpful Training Video on PDF Accessibility from AccessIT (requires Windows Media Player): “PDF Accessibility” a presentation by Terry Thompson, Technology Specialist with AccessIT, offers detailed help with evaluating PDF files for accessibility and creating accessible PDF using MS Word and Adobe Acrobat plug-ins.
Resources from Microsoft.
Microsoft’s Accessibility Web site: Read about accessibility in Microsoft products and compatible assistive technology products. Microsoft’s Accessibility Web site:
Of particular note in this site:
Resources from Adobe.
Access Adobe, a jumping-off point for information on the features and capabilities of Adobe products that enhance electronic document accessibility for people with disabilities such as blindness, low vision, and motor impairments. There are also links to resources that help people with disabilities work more effectively with Adobe software and aid authors in optimizing content for accessibility.
Adobe offers a variety of training materials for both students and those who wish to train others in creating accessible PDFs. The online training modules cover:
Movies/Streaming Training Videos (discusses Acrobat 5.0)
The guidelines and standards presented in this document are based on The Ohio State University Web Accessibility Policy and Standards (effective June 30, 2004). The WAC offers a detailed guide to the OSU standards.
Information about Section 508: Standards for Electronic and Information Technology
Guide to the Section 508 Standards for Electronic and Information Technology from The Access Board, a federal agency committed to accessible design.
Section 508: The Road to Accessibility. The Center for Information Technology Accommodation (CITA), in the U.S. General Services Administration's Office of Government-wide Policy, has been charged with the task of educating Federal employees and building the infrastructure necessary to support Section 508 implementation. Using this web site, Federal employees and the public can access resources for understanding and implementing the requirements of Section 508.
OSU Web Accessibility Center (WAC)
1760 Neil Ave 150 Pomerene Hall Columbus, Ohio 43210
Phone: (614) 292-1760 Fax: (614) 292-4190 E-mail: firstname.lastname@example.org
For questions or problems with this site, including incompatibility with assistive technology, email the WAC Webmaster.