This is an app for school to view a specific ebook format in iPad. The file extension for the app is .book which is combined PDF and other meta-data including XML, textbook categories, book cover thumbnail images and book titles. The school can download the subscribed eTextbook from the given Dropbox account. Also, it(.book file) can be transferred to app through iTunes. PDF in .book file is encrypted with a fixed 32 digits password. The app read and decrypted the content with the given password. Other PDF readers cannot display the content without the password even the PDF file is extracted from .book file. For details, please refer to the user guide.