Proxy Auto Configuration is a means to use a JavaScript function to
determine the proxy to use based on the requested URL.
It is described in detail here:
http://home.netscape.com/eng/mozilla/2.0/relnotes/demo/proxy-live.html

Also implemented by this library are parts of the now expired Internet Draft
at http://www.wrec.org/Drafts/draft-cooper-webi-wpad-00.txt about WPAD
(Web Proxy Automatic Discovery). The discovery implemented discovery methods
are DHCP and DNS "Well known Aliases".