Currently there is no easy way to mix "AND's" and "OR's", yet a typical validation logic for us is something like "if the computer is in room 1 OR 2 OR 3 AND the file does not exist, then install"
If there was a way to nest the AND's and OR's or logically grou them it would make life easier (currently we have to do either a rule for each room (i.e. if room1 and file does not exist, if room 2 and file does not exist, etc.) or we have to nest them (i.e. outer element is "if room 1 or 2 or 3) and inner element is "if file does not exist)