11-30-2011 03:23 AM
Pass-through means that you use SQL flavor of the remote RDBS in question.
If you want for some reason (not obvious to me) to access a flat file from within the RDBMS, you have to refer the specific documentation for that database.
12-01-2011 09:07 AM
I'm sure that the responsible DBA for that database (whatever that is...?) on your site can provide any useful information to you.