
You should only use it with the title attribute, a la W3, but it is very useful - FF adds styling to it by default and you can style it yourself - convention says to use a dashed bottom border.
It is required for even level 1 WAI compliance
( ,
Sat 1 Dec 2007, 0:40,
archived)
It is required for even level 1 WAI compliance

so it gives some mouseover text explaining the acronym. Alright, I like it now.
( ,
Sat 1 Dec 2007, 0:44,
archived)