top = window.top

It's the top most page in the current window.
For example, you could have a page nested in a page nested in a page
(using IFrames) etc and you could always refer to the top most page
(your frame layout) from any of those pages using window.top.

If you simply want to reload the contents of the window using the exact
same contents you can use top.<framename>.document.location =
window.location. This will include the original query string.  If you
want to exclude the query string use window.location.pathname.

mike