A CSD viewer embedded in UMD which is a data media of PSP® You can search various electronic documents and various contents in PC at PSP®. It can convert document in PC to CSD through CSD conversion service that is serviced through Internet and transfer it to PSP®. And it can download various contents converted to CSD like as magazine, comic, study material etc from service site to PSP®. It supports basic functions of CSD viewer like as enlargement/abridgement, page movement, bookmark, etc and can search document conveniently. Furthermore, user can do examination problem solving, score, answer and answer check through learning function thus supporting true e-Learning functions.