"network.proxy.type" is a configuration option for the Firefox web browser; it accepts an integer.
Determines how the browser uses proxies.
0 (default): Direct connection to the Internet (no proxy used)
1: Manual proxy configuration (use values in network.proxy.*)
2: Autoconfiguration by URL (use value in network.proxy.autoconfig_url)
3: Same as 0 for compatibility reasons (see bug 115720) and will be reset to 0
4: Auto-detect proxy settings for this network