From the PROXOMITRON HELP FILE:
http://file//path
Used to filter a local file as if it were a web page. Similar to the file:// URL used by most browsers.
So, to filter C:Temppage.html , you would use http://file//c:/temp/page.html (note: this does not work in Opera, as far as I can tell. It does work in MSIE and Mozilla, so should work in Netscape.)
To debug, bypass, or use other HTML commands in conjunction with this: http://dbug..file//c:/temp/page.html