When I delete and reinstall Javelin on iPad, then download a .drmz file, it asks for a code. But, doing the same on PC does not ask for a code. Why?

The reason is that on a PC the data relating to authorization is stored in the Windows registry, whereas on mobile devices it is stored with a file within the Javelin folder (they don’t have an equivalent to a registry), so after you delete it the authorization data is lost also. If you want to delete a file on a mobile device and retain the authorization information, simply touch and hold the cover of the file in question, until a pop-up menu appears. Then select DELETE from this pop-up menu and the file will be removed, but the authorization details will be retained. If you simply wish to refresh the file, do the same and select the REFRESH FILE option on the pop-up menu. And if the file should be in the catalog and you cannot see it, try refreshing the catalog (which re-downloads it automatically) by touching the refresh icon at the top right of the catalog (the curly icon).