The page contains at least one table that is supposed to be for layout purposes (i.e. it does not contain CAPTION, THEAD, TH and TFOOT).

When linearized, its contents should be read in the expected order and should make sense.

Make sure that, when linearized, the content of the layout tables used in the page can be read in the appropriate order. This is conceptually easy: just imagine stripping out all of the tags.

In certain cases, it is also possible to check by running a piece of paper down the page and reading the page line by line to provide some clues of possible problems.

Consider that tables used to present tabular data should not be linearized as suggested here. They have to be appropriately marked up (with TH, SCOPE, AXIS, ID and HEADERS tags and attributes) to be accessible. Other tests within this program implement the appropriate WCAG or Section 508 guidelines.

Often when accessibility is considered only after page templates have been defined and implemented, the table organization used to lay out the content on a page does not function properly with non-graphical browsers.

The most common mistake is to forget that HTML tables lay out the information row by row.

Non-graphical browsers follow the row by row order when presenting the content of the table. Even if visual clues would suggest a column by column reading order.

Consider the following example (from HTML Techniques for Web Content Accessibility Guidelines 1.0 [http://www.w3.org/TR/WCAG10-HTML-TECHS/#tables-layout] ):

... if a table is rendered like this on the screen:

There is a 30% chance of               Classes at the University of Wisconsin 
rain showers this morning, but they    will resume on September 3rd. 
should stop before the weekend.

This might be read by a screen reader as:

There is a 30% chance of Classes at the University of Wisconsin
rain showers this morning, but they will resume on September 3rd. 
should stop before the weekend.

Linearization is the process of transforming a two-dimensional structure, like a table, into a mono-dimensional structure. It is the process that any speaking browser or screen reader has to follow in order to render the content of the page via audio.