Table accessibility principles

Table accessibility is important to people with the following disabilities:

• Blindness
• Low vision
• Cognitive impairments

When presented meaningfully, tabular content is of benefit to many users and can increase a person’s cognitive ability to understand complex information being presented. When tables are used in an accessible manner, they can also support and add meaning to page content. For example, the information conveyed in a graphical image can be difficult to adequately represent in the ALT attribute but if the alternative is provided in an accessible data table the equivalent information is then fully accessible to the screen reader user.

Descriptive and meaningful headings should be provided for information presented in data table format. All users benefit from this, however, in addition, when data tables are coded using TH, ID, SUMMARY and CAPTION the accessibility of tabular data for users of assistive technology is also greatly improved.

To effectively assess the accessibility of a table it is first necessary to identify the nature or purpose of the table. There are two types of tables commonly used: Data tables and Layout tables:

• Data tables are used to present tabular data, often numeric, in an easy-to-understand format. The meaning of a piece of content is affected by its relationship to the table column and row headings; and
• Layout tables are used to present, space or “lay-out” page content and can be purely decorative. The arrangement or position of information within a layout table should have little or no bearing or impact on its meaning.

Data tables

Data tables should only be used to present data. In order to understand the data in the table the column and row headings are required. Data tables can be simple or complex.

Simple data tables

A simple data table can be thought of as having one row of column headings and/or one column of row headings:-

Figure 1: Example of a simple data table with a single row of column headings

Complex data tables

A complex data table may have multiple columns or row headings nested within other columns or rows:

Figure 2: Example of a complex data table with multiple column headings and nested sub headings

Accessibility principles specific to the use of data tables include, but are not limited to:

• Data tables are used appropriately and coded correctly.
  • Data tables should always be coded with appropriate TH, SUMMARY and CAPTION;
  • Ensure there are no empty table headers and no empty rows in a data table;
  • Avoid excessive nesting of tables; and
  • Data table headings should be concise but descriptive.
• Complex data tables are supported with additional information
  • Ensure that TH ID and TD HEADERS are used; and
  • Additional explanatory information is provided within the page content to aid understanding of the table content.

Layout tables

Layout tables are used to present, space or “lay-out” a page. Layout tables are used to control the placement of content only. For instance, the content of each row of a layout table is meaningful when moving from left to right.

For example a screen reader would read the following table as:

Name, AccessibilityOz, Website, www.accessibilityoz.com.au, phone 03 8677 0828.

Whereas, in the next example, the information is not presented meaningfully for a layout table and a screen reader would read:

Name, Website, phone, AccessibilityOz, www.accessibilityoz.com.au, 03 8677 0828.

In this example the information should be coded in data table format.

Accessibility principles specific to the use of layout tables include, but are not limited to:

• Layout tables are used appropriately and coded correctly.
  • Layout tables must not have column headings;
  • Layout tables must not be coded with TH, SUMMARY or CAPTION;
  • If used to present text content, make sure that the layout table is structured in a meaningful way i.e. content makes sense when read cell to cell, left to right; and
  • Layout tables must not be used to present mathematical formula.
  • Layout tables must not consist of a single cell alone.