This goes in the functions if you need to allow other file types to upload to the library. The example adds two e-book formats.
// add types to allowed uploads add_filter('upload_mimes', 'custom_upload_mimes'); function custom_upload_mimes ( $existing_mimes=array() ) { // add the file extension to the array $existing_mimes['epub'] = 'mime/type'; $existing_mimes['prc'] = 'mime/type'; // call the modified list of extensions return $existing_mimes; }