Syntax: one or more filenames separated by space
Set the filename assumed for directory URLs. The default is
``index.html
'' and ``index.htm
''. This filename will be removed from stored URLs
to prevent redundant fetches of the page. So the URLs
``http://www.mysite.com/fun/
'' and
``http://www.mysite.com/fun/index.html
'' will be considered the
same and only be fetched once (as http://www.mysite.com/fun/
).