It is possible in jAlbum to add objects to an album project that can't actually be displayed in a browser, or that can be displayed only if a particular browser plugin is present. Objects like PDF files, MS Word documents, and zip files fall into this category. Adding a video file but having jAlbum video support turned off produces a similar situation. The skin is built to accommodate unsupported album objects, but because the results are unpredictable (you can't control how a site visitor's browser is configured), including unsupported album objects is generally not recommended.
If you add an unsupported album object to the project, jAlbum assigns an icon to it, based on the type of object. By adding a THM file with the same base name, you can choose another image to represent the object. For example, mylicense.pdf could be added to the project along with mylicense.thm, where that is simply an ordinary JPG file with its file extension changed.
The skin displays this icon or representing image as the thumbnail on the index page. Clicking on the thumbnail calls the file in question. What happens next is entirely dependent upon the site visitor's browser configuration. Clicking on the icon for a PDF file, for example, might open the file in a new tab in the browser, it might open the file in a PDF reader application, or it might prompt the visitor to save the file. This cannot be controlled by the coding on the page.
There will be a slide page for the object, accessible from neighboring slide pages by clicking "Next" or "Previous." This page displays the icon or representing image, and there will be an icon on the page that opens the file, in exactly the way the index page thumbnail opens the file.