Tables Overview

Types of Tables

Tables are used primarily on the Web for two purposes:

• Layout or organization of items on the screen
• Presenting data

The two types of tables discussed in today's Webinar include tables found in:

• Web pages or HTML documents
• PDF documents

Specifications, Recommendations, and Regulations

HTML, of course, is the publishing language of the Web. Specifications and table recommendations are found in a few different places, including:

• The World Wide Web Consortium's HTML 4.01 table guidelines
• Techniques for Web Content Accessibility Guidelines (WCAG 2.0)
• H39: Using caption elements to associate data table captions with data tables
• H43: Using id and headers attributes to associate data cells with header cells in data tables
• H63: Using the scope attribute to associate header cells and data cells in data tables
• H73: Using the summary attribute of the table element to give an overview of data tables
• Section 508 Standards
• §1194.21 Software applications and operating systems.
• § 1194.22 Web-based intranet and internet information and applications.
• (g) Row and column headers shall be identified for data tables
• (h) Markup shall be used to associate data cells and header cells for data tables that have two or more logical levels of row or column headers
• (m) When a web page requires that an applet, plug-in or other application be present on the client system to interpret page content, the page must provide a link to a plug-in or applet that complies with §1194.21(a) through (l). For pages that have links to PDF documents.

PDF stands for Portable Document Format. PDF files are found on the Web in many places, especially when an author wants the document to maintain the original formatting of fonts, sizing, colors, and layout of the page or form.

A couple of PDF resources that include instructions for accessible tables are listed below:

• Adobe Acrobat® 9 Pro Accessibility Guide: Best Practices for Accessibility (PDF, 1.3M)
  Look for the section "Using the TouchUp Reading Order Tool Table Editor"
• Accessible and Usable PDF Documents: Techniques for Document Authors, by Karen McCall, M.Ed., ISBN 0-9738246-1-1

JAWS Uses Virtual Cursor Technology to Read HTML and PDF Documents

So how do JAWS or MAGic users actually handle reading tables on the Web or in PDF documents? Since there is no visible cursor in most Web pages or PDF documents, JAWS and MAGic use virtual cursor technology. The virtual cursor is a simulated, invisible cursor used when working in HTML or PDF documents, and makes it easy to browse the Internet and locate information.

Table Reading Keystrokes

Choose this link to open a file containing table reading keystrokes for JAWS and MAGic.

How JAWS Detects Tables

JAWS uses logic to try and filter out layout tables. But JAWS can be set to detect only data tables, or to detect all tables, including tables used to format the layout of the page. The nesting level of each table is also announced. Tables are often used to provide page layout formatting, so setting this option to All Tables can provide a lot of information on some pages.

The things that determine a data table for JAWS include the following:

1. If the table tag uses a datatable="1" or datatable="TRUE" attribute then it is assumed to be a data table.
2. Next, the number of valid cells are counted; there must be at least two rows with a valid cell count.
3. A cell is valid if both its rect can be obtained and its rect is between 200 and 16000 pixels, or if its rect can't be obtained and it contains text. (Cells only containing graphics are not considered valid.)
4. A row is valid if it contains at least two valid cells.

The table below is an example of a layout table:

EXERCISE: Press T to look for tables on the page. Did you find any?

Press INSERT+V and change JAWS from Layout Tables - Off to Layout Tables - On.

Repeat the process above. Also notice the JAWS announcements prior to and after the table. What does JAWS announce?

This option controls whether or not JAWS recognizes tables used exclusively for formatting purposes. Such tables are often used as navigation bars at the top, bottom, or side of the Web page and for placement of graphics or other objects on the page.

What Does a JAWS User Hear When They Encounter A Table?

A JAWS user can press the navigation quick key letter T to move directly to a table. When they do they hear the following information automatically:

1. Caption (if present)
2. Summary (if present)
3. Coordinates and then the contents of the first cell

JAWS gathers this information from the various parts of the HTML code and presents it sequentially. The virtual cursor is placed in the first cell of the table at the beginning of any text that is present.

Download Adobe Reader

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