Which attribute to take for a tooltip text

[Jukka K. Korpela]

This is what the specification says:

Anyone who wishes to comment on the issue should be expected to have read
that long ago.

It's also worth to note, that FF, NN and Opera display the <abbr> and
<acronym> elements with the title attribute set, underlined with a gray
dotted line; enough reason to move the mouse over those elements ...

For how many people? 10 % of users maybe? Assuming they guess correctly what
the dotted line that looks like some mistake is supposed to say. And assuming
they have some reason to expect that there is something _useful_ in the
tooltips.

Besides, the dotted underline is part of the problem rather than part of any
solution. The browsers don't even care to suppress it on printing by default.