Note that document.location is a synonym for document.URL. Netscape will remove document.location in a future version of their browser. However MSIE3 only understands document.location.
The script is not without any problems. When a site frames your site, a small problem related to the back-button, will occur in these browsers: Netscape 2, 3 and MSIE 3, 4. The problem is, that the user cannot get back to the site who framed your site. The problem is not present in Netscape 4.
When another site frames your site, your site will pop-up in a new browser-window. The file escaped.htm will be displayed in the frame of the other site. It should contain some simple text like: Thanks for visiting our site..