If it is left blank, an empty page will be opened. It can be used to reference the new window from the current window. The third parameter is a list of options. To enable them simply include them in the list or assign them a value of 1. A value of 0 will disable them.
Some options require a value.
Sets the inner height of the window in pixels. Sets the outer height in pixels. The window will float below other windows. The window will float above other windows. When the window.open function executes successfully, it will return the link to the window so that it can be accessed from the parent window.