lang_before_translation not documented

[threadi]

Hi,

i searched for the possibility to show a link to the main language within the language-selector. in helper.php i found the following in line 44:

// get default translation
        if(!$conf['lang_before_translation']) {
            $dfl = $conf['lang'];
        } else {
            $dfl = $conf['lang_before_translation'];
        }

If i set "lang_before_translation" in my local.php to "de" i get what i want.

But is that the desired functionality? Or it is an old relict and changed simply to $dfl = $conf["lang"]?