Corrections to Chapter 21
The "TIP" on page 533, which describes how to use the frameborder attribute in a cross-browser environment, is a bit confusing: the following explanation may help you out.
Internet Explorer 3 treats both values frameborder="yes" and "no" as equivalent to "0" (or 'no') -- that is, both values cause the borders to disappear. Thus, using frameborder="no" will eliminate the frame border on all browsers. Since the default behavior is to have frameborders present, simply omitting the frameborder attribute will ensure that the borders are displayed.
Thanks to Dan Horth for pointing out the rather confusing nature of the TIP as presented in the book.