Autoconfigure Scripts for Proxy Settings - Apr. 22, 2004
http://nscsysop.hypermart.net/proxypac.html

Navigator Proxy Auto-Config File Format
http://wp.netscape.com/eng/mozilla/2.0/relnotes/demo/proxy-live.html

JavaScript or JScript Auto-Proxy Example Files
http://www.microsoft.com/windows/ieak/techinfo/deploy/60/en/corpexjs.mspx