Universal Web Pages:

Guidelines for Exceptions

Presenting documents in standard markup language allows every person with a browser to read the documents.  However, there are instances when alternative formats are needed.  These guidelines illustrate how best to present information in alternative formats.

Include file information.

When linking to a document in an alternative format to HTML (such as PDF or RTF), include a text description of the document, with the name, file type, file size, and effective date where appropriate. This will ensure that visitors have a reasonable understanding of what to expect when they view the material. 

Examples:

    • Facts for Features: Women’s History Month, May 2006 [PDF - 72K]
    • Hawaii Population Estimates:  Excel (16K) | CSV (1K)

The preceding examples tell the user the subject, the file size, and the format to expect, before they actually attempt to download it.

Use appropriate formats.

Where alternative formats are needed, open formats are best because they are available to a broad base of applications on multiple platforms, thereby making  the data available to a broad spectrum of users without additional cost.  This is not always the case with closed, proprietary formats that are processed by a limited number of programs from specific vendors. 

Some commonly used open formats are listed below.  Because some may be more broadly accessible than others, you should research them carefully before deciding what format is best suited to your needs.  This list is not inclusive of all open formats.

Open formats for mathematical documents:

    • TeX, LaTeX
    • Device Independent format (DVI)

Open formats for word processing documents:

    • OASIS Open Document Format for Office Applications (ODF).  This is an XML-based open document format for text, spreadsheets, databases, charts, and presentations.  It is supported by the Organization for the Advancement of Structured Information Standards (OASIS), an industry consortium.
    • Rich Text Format (RTF)

Open formats for highly formatted documents, especially those intended for printing, where appearance and formatting must remain unchanged across platforms:

    • PostScript (PS)
    • Portable Document Format (PDF)

Open formats for images:

    • Joint Photographic Expert Group (JPEG)
    • Portable Network Graphics (PNG)
    • Scalable Vector Graphics (SVG)

Open formats for audio and video information:

    • Ogg Vorbis (OGG)
    • Musepack (MPC)
    • Free Lossless Audio Codec (FLAC)
    • Speex
    • MPEG (Moving Picture Experts Group)

Best Practice for Particular Types of Documents

PDF documents

When there is a clear business need, agencies may use Portable Document Format (PDF).  For example, this format is appropriate where it is important to retain the original formatting of a document, where security measures must be placed within the document, or where the document is long and it is likely that readers will prefer to print out the document for later reading rather than read the text on-screen. 

    • Provide a link to the downloadable free viewer.
    • To ensure maximum accessibility, also provide an HTML version of the document whenever feasible.  
    • Organize the document for ease of use and downloading.  In most cases, large or complex PDF documents (generally, more than 5-10 print pages), are best organized in sections or chapters and linked together. One option is to provide a summary of each chapter in HTML and then provide the full chapter text in PDF. That way, readers will know what the content is about before they commit to downloading the PDF file. It is still important to provide a link to download the entire document since some readers may prefer to print the entire document for later reading. 
    • PDF files must still adhere to accessibility requirements.  Use PDF tagging techniques to maximize accessibility.  More information on this is available at the Adobe web site.  There are also third party products to improve PDF tagging.   Tagged PDFs should be tested with screen readers to assure that they have been tagged and ordered properly.

Data files

There is often a business need to offer information in formats that will allow processing of data after downloading, or particular modes of display.  Some examples of such formats include spreadsheets, word processing documents, and slide presentations.  Use of such formats may facilitate off-line analysis or manipulation.  Disseminating data and materials for downloading in open formats will make the materials available to the widest possible audience.

When choosing the format(s), consider: (1) the intended use of the data by the website's visitors; (2) the frequency of use by the Web site's visitors; (3) the accessibility of the format to the Web site's visitors; and (4) the level of effort and time required by the organization to convert the data to the file format.

Use a proprietary format (for example, SAS, SPSS, SQL, MS Excel, MS Word, etc.) only if the format provides functionality not otherwise available.  If you must use a proprietary format, ensure that the intended audience is known to have ready access to the appropriate software.  Always provide a link to download the appropriate viewer, plug-in, or related software.   Be aware that not all viewers or plug-ins for proprietary formats are available for multiple platforms.  Plug-ins for open formats have the widest availability.

Streaming audio/video

Use of a streaming audio/video plug-in presents a problem of system compatibility. The only plug-in that currently is available for all operating systems is Real Media (Real One format). Using Microsoft’s Media player restricts your audience exclusively to Windows users.  Using Quicktime restricts your audience to Mac or Windows users.  There are many large organizations using UNIX or other operating systems.  Where there is no alternative to using such limited-availability formats, multiple formats should be offered to make the information available to as wide a spectrum of users as possible.

Department of Commerce Web Advisory Council (WAC)
U.S. Department of Commerce

Send questions and comments about this page to WAC@doc.gov
Page last updated October 12, 2010