How do I link to the root directory of the server?

Hi, I have a file called application.php and in this file I define all of the directories in my site: class object {}; $CFG = new object; $CFG->wwwroot = http://www.mydomain.com; $CFG->dirroot = "/usr/home/myaccount/public_html"; $CFG->admindir = "$CFG->wwwroot/admin"; $CFG->claimsdir_adm = "$CFG->admindir/claims"; $CFG->clientsdir = "$CFG->admindir/clients"; $CFG->cssdir = "$CFG->wwwroot/css"; $CFG->expense_categoriesdir = "$CFG->admindir/expense_categories"; $CFG->projectsdir = "$CFG->admindir/projects"; $CFG->shoppingdir = "$CFG->wwwroot/shopping"; ... This works very well and means if I change a directory name or move a directory I only have to update this file. application.php is included on every page so all I have to do to link to another directory would be something like: <p>Click <a href="<?php echo $CFG->expense_categoriesdir; ?>?action=add_expense_category">here</a> to add a category</p> The problem with this is that the URL's include the http://www.mydomain.com/ and are therefore not relative links. Is there a way to link to the root directory from wherever I am within the directory structure? Thanks for your advice