Therefore I need a (simple) explanation how to pass multiple selections from a list to my Ajax-script - if there are any simple solutions.
I'm not using any kind of framework - just plain Ajax/JS, PHP and of course HTML.
how about you show us your ajax script?
The point here is that I'm not having a script yet - only a script to check for Ajax support.
(If I had a script I wouln't have asked, have I? ;) )