From MozillaZine Knowledge Base
When using a single proxy for all HTTP traffic is not flexible enough, or if you need to centrally administer proxy settings for a network or organization, PAC (Proxy AutoConfiguration) files allow you to choose a proxy via script.
This preference points to a PAC file to be used by Mozilla when network.proxy.type is set to 2.
Possible values and their effects
A URL (remote or local) to a valid PAC file. Default is an empty string.
Mozilla Firefox 1.5
The field “Automatic proxy configuration URL” under “Tools → Options → General → Connection → Connection Settings...”
The field “Automatic proxy configuration URL” under “Edit → Preferences → Advanced → Proxies”
Although this preference worked in Netscape Communicator, it did nothing in Mozilla until PAC functionality was implemented (see check-in date below).
First checked in
Has an effect in