Educational entities often struggle with questions as to which file formats are best for distributing online materials. Traditionally, online documents have been delivered primarily using HTML. However, a growing number of documents in education are distributed in other formats, such as Adobe Portable Document File (PDF) and Microsoft Word. Whether these file formats are accessible is not a simple question with a yes or no answer. For guidance in making this determination, see the AccessIT Knowledge Base articles Is PDF accessible?  and How accessible are Microsoft Word documents? 
Additional guidance comes from the growing number of states that have passed laws or implemented purchasing policies that address textbook accessibility in both postsecondary and K-12 education. These laws have arisen from one of the key challenges faced by many students with disabilities: obtaining academic print materials in an alternate format. Students who are unable to read standard print (for instance, students with blindness, low vision, or learning disabilities) require their materials in an alternate format, such as Braille, large print, or audio. Increasingly, the medium of choice is electronic text, since students with print disabilities can read, navigate, and search the text using off-the-shelf information technology, perhaps in combination with assistive technologies such as synthesized speech.
States vary in their approach to legislating this problem. Some states simply require that publishers provide electronic versions of printed textbooks upon request (for example, see California Assembly Bill 422  and Washington SB 6501 ), while others give preferential procurement status to publishers providing alternative formats for textbooks (see Kentucky SB 243 , only available as a Microsoft Word document).
For a list of accessible textbook laws in all fifty states, see the report U.S. States and Territories Accessible Curriculum Survey  from CAST (founded as the Center for Applied Special Technology). Also, the National Center on Accessing the General Curriculum (NCAC) at CAST has produced several research papers regarding the impact of existing policies on access to, participation in, and progress within the general education curriculum. Consult the Policy section of the NCAC Publications  website for a complete listing. A particularly relevant resource is their NCAC Policy Group White Paper for Policy, Property & Permissions , which includes detailed profiles of the accessible textbook efforts in California, New York, Massachusetts, Texas, and Kentucky.
Kentucky SB 243 and its accompanying regulations  (704 KAR 3:455) marked the first time a state had formally documented a hierarchy of file formats based on their inherent accessibility. Prior to this, laws had documented general requirements of chosen file formats, but provided little or no guidance as to which file formats best met this requirement. One common criterion in the textbook laws for measuring the accessibility of file formats is that file formats must preserve documents' "structural integrity." A standard definition of this concept, applied with slight variation in several state laws, is this (quoted from WA SB 6501 ):
"Structural integrity" means all instructional material, including but not limited to the text of the material, sidebars, the table of contents, chapter headings and subheadings, footnotes, indexes, glossaries, graphs, charts, illustrations, pictures, equations, formulas, and bibliographies.
Some laws that require "structural integrity" explicitly define a default file format to be used if the publisher and educational entity fail to agree as to which file format best supports the requirement. In California AB 422, the default is ASCII, whereas Washington SB 6501 favors "a verified and valid HTML format." The Kentucky regulations provide much more extensive guidance about the accessibility of file formats by establishing three levels of compliance:
- Level 1 ("full compliance") includes XML, XHTML, or HTML format.
- Level 2 ("provisional compliance") includes RTF or Microsoft Word.
- Level 3 ("marginal compliance") includes "unlocked PDF."
Both Kentucky's K-12 and postsecondary laws are profiled in more detail elsewhere in the AccessIT Knowledge Base:
- The Kentucky Postsecondary Textbook Accessibility Act: A Promising Practice on Textbook Accessibility Legislation 
- Kentucky's K-12 Accessible Textbook Law: A Promising Practice on Accessibility Law for K-12 
New York later implemented a similar approach to Kentucky's in Chapter 219 of its Education Laws of 2003 , though its order of file formats differed from that of Kentucky. New York identified full-text DAISY 3 as the preferred file format, followed by HTML, then by "structured PDF," and then by "Microsoft Word or ASCII." Notice that the order of PDF and Word is the reverse of the order in Kentucky.
DAISY 3 is a standard format for digital talking books. It is an XML language that allows human narration to be marked up so that it's easily navigable, and it optionally allows for synchronization of the narration with the full text of the document so that it's fully searchable. E-text readers can easily navigate through DAISY 3 documents with full appreciation of its organizational structure. More information about DAISY is available from the DAISY Consortium . With the reauthorization of IDEA in 2004, the U.S. government called for a "National Instructional Materials Accessibility Standard" (NIMAS) and subsequently charged CAST with creating the standard, which it has done and which is an extension of DAISY 3. Since this is a federal standard, publishers should be better able to systematically address the needs of students with disabilities nationwide, without the challenges associated with delivering different types of accessible documents to different states because of the variance in state laws.
-  Is PDF accessible?
-  How accessible are Microsoft Word documents?
-  California Assembly Bill 422
-  Washington SB 6501
-  Kentucky SB 243
-  U.S. States and Territories Accessible Curriculum Survey
-  NCAC Publications
-  NCAC Policy Group White Paper for Policy, Property & Permissions
-  accompanying regulations
-  WA SB 6501
-  The Kentucky Postsecondary Textbook Accessibility Act: A Promising Practice on Textbook Accessibility Legislation
-  Kentucky's K-12 Accessible Textbook Law: A Promising Practice on Accessibility Law for K-12
-  Chapter 219 of its Education Laws of 2003
-  DAISY Consortium