$conf['batch_download_max_elements']

Maximum value of the Maximum number of photos per download set slider.
Default is 1000.

$conf['batch_download_max_size']

Maximum value of the Maximum size of each archive slider.
Default is 500.

$conf['batch_download_additional_ext']

Array containing downloadable file extensions (case sensitive).
Default is $conf['picture_ext'].

$conf['batch_download_file_pattern']

Pattern for filenames in the archive.
Available fields are %id%, %filename%, %author%, %dimensions%.
Available functions are $escape(xxx), $upper(xxx), $lower(xxx), $strpad(xxx, z, c).
Default value is %id%_%filename%_%dimensions%.
Example: $strpad(%id%,4,0)_$escape(%filename%)_$lower(%author%)_%dimensions%.