User Agent Support Notes for Common Failures

The blink value of the text-decoration property is not supported by Internet Explorer. It is supported in Netscape/Mozilla family browsers. Not tested in others (e.g., Safari, Opera).

Internet Explorer 6 also triggers the onclick event when a radio button with onclick receives focus; adding other event handlers (onxxx attributes) to prevent this does not work.

The blink element is not supported by Internet Explorer 6 on Windows. It is supported in Netscape/Mozilla family of user agents and Opera on Windows.

Early screen readers literally read Web content from the screen, which lead to problems when tables were used for layout where one table cell was meant to be read in its entirety before reading the next table cell. Today's screen readers work with the underlying markup, which means that they do read a table cell in its entirety before moving on to the next cell, but layout tables may still inadvertently introduce problems with the natural reading order of the content.

The Refresh header is not defined in HTTP/1.1 or HTTP/1.0, but it is widely supported by browsers (tested in Firefox 1.0 and IE 6 on Windows).

:before and :after are not supported by IE7 and lower

Screen reader support for navigating data tables with and without correct header mark-up varies.

• JAWS has many keyboard shortcuts to navigate between data cells and read associated header information. The default behavior for JAWS with version 12 and later is to read only headers that have been properly marked as headers by the author of a table.

• Window-Eyes has different customization options for row and column announcement: both column and row headers, just column or just row headers, just the header that changes, and even defining a specific row or column to compensate for missing markup. For example, "R 1, C 1" would be the first row and column of the table.

• VoiceOver announces column headers when traversing a table horizontally. It does not currently read row headers even when they are marked up, though it will identify the row number.

• NVDA has shortcuts for moving between table cells horizontally or vertically, reading the header that changes when navigating. When moving through data cells vertically, NVDA (2011.3 with Firefox 11) will read the first cell of a row even when it is not marked up as header. However, when moving through data cells horizontally, it will only read out the cells in the first row as column headers if they are correctly marked up.