It would be much easier if you started with the already existing description and get used to the export function, editing a script and what to see in the output as I do not feel that I could anything substantial to the description in the documentation:
If you then get stuck with a particular problem then it will be much more effective to discuss that problem than to offer a suggestion and you do not know what to do with it, e.g. this would create an alphabetic list of artists for all the selected files in which each name appears only once:
$filename(artists.txt,utf-8)
$loop(%artist%,1)%artist%
$loopend()