November 22, 2003
The HTML tags <blink> and <marquee>, as you probably know, should never be used.
"Note. If blinking content (e.g., a headline that appears and disappears at regular intervals) is used, provide a mechanism for stopping the blinking. In CSS, 'text-decoration: blink' will cause content to blink and will allow users to stop the effect by turning off style sheets or overriding the rule in a user style sheet. Do not use the BLINK and MARQUEE elements. These elements are not part of any W3C specification for HTML (i.e., they are non-standard elements)."
Source: www.w3.org/WAI/GL/WD-WCAG10-TECHS-20000615/css-techniques.html
CSS1, CSS2 and CSS2.1 currently have blink included as a value for the text-decoration property. CSS3 will probably include this as well. This is what CSS1 says about text-decoration: blink;:
"UAs must recognize the keyword 'blink', but are not required to support the blink effect."
CSS2:
"Conforming user agents are not required to support this value."
CSS2.1:
Conforming user agents may simply not blink the text. Note that not blinking the text is one technique to satisfy checkpoint 3.3 of WAI-UAAG."
CSS3:
"Conforming user agents MAY simply not blink the text."
Source: www.w3.org/TR/2003/CR-css3-text-20030514/#text-decoration
So far, I like CSS2.1's statement best. I've not really made up my mind about whether or not CSS3 should include blink; on one hand, it follows the philosophy of separating style from content; on the other hand, it's a usability issue. Blinking text is simply annoying. On the gripping hand, people can enable their user style sheets and override it by doing text-decoration: none;. So I'm honestly not sure.
In addition to this, CSS3 currently has a marquee property. Whether this is a good thing is also debatable. At least it seems to be well thought out.