The creator code & file type is built into the document in order for the OS to recognize, launch & open the document by double clicking on the file. That's why the MAC files arn't particularly sensitive to the 3 letter extension code following the end of a file name. In MAC OS you can double-click almost any file (preferrences, data, document, etc.), with or without extension deliniater, and the proper app will launch. It has been this way for many years. I believe that WIN95 initiated a limited capability for doing this, providing that the extension is correct and its not a "generic" file type (like an eps file)? The "problem" with the MAC Pozer files is akin to a WIN Pozer file haveing a corrupt or missing RSR file. Not sure if that's an easy thing to "fix" on a PC but it can be done with the Applescripts, ResEdit or MaConverter for MAC OS.