popup(<top>, <left>, <width>, <height>, <url>)
Pop up a window above the current contents of the browser. This is a pop-up. <top> is pixels to position the new window from the top of the current window <left> is pixels to position the window from the left of the current window <width> is width of the new window in pixels <height> is height of the new window in pixels <url> is the place where the window content will be retrieved. Because this is a separate window, the URL can be on any site.
The following ruleset shows popup() being used
The following demonstrates the preceding rule: