ALT text in Introduction to WD-WAI-PAGEAUTH

In the introduction to [1], you say:

  User agents can render "alt" text as a tool tip, thus providing
  additional information to the general populace.

I think recommending that alt text be rendered as a tooltip is a bad
idea, since it will encourage authors to write alt text that is
suitable for a tooltip rather than alt text suitable for replacing an
image.  (The title attribute is generally considered more appropriate
for tooltips, I think.)

David Baron

[1] http://www.w3.org/TR/1999/WD-WAI-PAGEAUTH-19990226