Create tables that transform gracefully

These checkpoints all deal with how to create tables that work in text and speech browsers.

The checkpoints are:

• For data tables, identify row and column headers [Priority 1]
• For data tables that have two or more logical levels of row or column headers, use markup to associate data cells and header cells [Priority 1]
• Do not use tables for layout unless the table makes sense when linearized. Otherwise, if the table does not make sense, provide an alternative equivalent (which may be a linearized version) [Priority 2]
• If a table is used for layout, do not use any structural markup for the purpose of visual formatting [Priority 2]
• Provide summaries for tables[Priority 3]
• Provide abbreviations for header labels [Priority 3]

Why the checkpoints are important

People who use screen readers, palmtops, or other devices, or who view only a portion of the page at a time (e.g., when using screen magnification or low-resolution) may have difficulty accessing information from pages with tables. For example:

• Users of text-only browsers or screen readers rely on the headers to gain an understanding of the table structure
• Unless tables are marked-up properly, they will not provide browsers with the appropriate information to support navigation among table cells and to access header in other table cell information

Tables were originally developed for presenting tabular data and not for controlling presentation. However, the data cells in a table can hold many different types of information, including text, numbers or images so designers often use tables to control page layout. For example, to present text in a newspaper-like column layout, to display navigation elements on the left of the page with content in the middle or to position images inside blocks of text.

This creates a problem for users of screen readers or older technology. Older screen readers and text only browsers can't cope with information laid out in columns. If two columns of text are laid out side-by-side, a sighted person will read the left hand column from top to bottom before moving on to the next column. An older screen reader or text only browser will read from left to right, starting with the first sentence on the left hand column, then running over into the first sentence on the right column. This continues all the way down the page. The end result is that sentence fragments are combined into meaningless gibberish.