Thanks, Slavok. It worked! I over complicated matters.

Thanks to ALL for the generous gift of your genius. I am in over my head but I am having fun. I would like to exclude the optional navigation links from guest viewing and I have attempted the solution from Slavok but this is the best I can do:

    // Are there any additional navlinks we should insert into the array before imploding it?
    if ($forum_user['is_guest'] = false)
    {if ($forum_config['o_additional_navlinks'] != '' && preg_match_all('#([0-9]+)\s*=\s*(.*?)\n#s', $forum_config['o_additional_navlinks']."\n", $extra_links))
    {
        // Insert any additional links into the $links array (at the correct index)
        $num_links = count($extra_links[1]);
        for ($i = 0; $i < $num_links; ++$i)
            array_insert($links, (int)$extra_links[1][$i], '<li id="navextra'.($i + 1).'">'.$extra_links[2][$i].'</li>');
    }}

Is it my syntax or am I too green to be going here? At the least, I do not know how to write the

if ($forum_user['is_guest'] = false)

argument.