language translations on php site

Set your own language preference [01-Mar-2003] Starting from today, your browser's "Accept Language" setting is also honored on language sensitive pages on the php.net site. If you would like to get to the documentation page of echo for example, you can use the /echo shortcut on all mirror sites, if your browser is set to provide your language preference information to the server. This also makes the PHP error message links point to the documentation in your preferred language. You can set your preferences under Edit/Preferences/Navigator/Languages in Mozilla, and under Tools/Internet Options/Languages in Internet Explorer. This will probably also enhance your web experience on sites providing translated content. i'm interested how this works , any ideas ?