[quote="leo"]I guess your Perl script knows the full path to the files, in which case you can add them to a collection explicitly instead of manufacturing a Find command that will do it.
Have a look at this thread for the commands:
[Is DOpus right for me?:: user-generated collection xml)[/quote]
Yep, this might just work.. 
I've seen it before, but didn't remember it.
However, this too complicated attempt to make this list at least show that there's an issue with the containing field, especially if wanting to run quiet queries.
Thank you for this solution, it saved me from struggling with the interfering containing field.