If you ever receive a Sybase Power Designer file (such as the pdm file from Jeff Tallman) but you don’t want to either purchase or install the full blown Power Designer, then I have an answer for you. It is the Power Designer Viewer from Sybase.
While it is free, you have to fill out a form to get access to the download. Sybase Sales will likely call you regarding purchasing a full blown version of Power Designer. If you’re not interested in purchasing it, just tell them – Sybase Sales People are generally very nice folk.