Relative Paths in Includes

Does anyone know the proper way to specify a move up/down from a relative path? I'm trying to do something like this and it does not work in 4.2.3: include_once '..\..\SomeFile.php' ; I get this error: "PHP Warning: Failed opening '..\..\XMLUtilities.php' for inclusion (include_path='.;c:\php4\pear') " _______________________________ This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system.