|To get data in file use: /ondemand/core/?method=CORE_ATTACHMENT_READ&rf=XML&object=29&objectcontext=[import ID - from above]&convert=1
This is assuming file is CSV and want back as XML - hence the &convert=1.
If you attached a file that was already XML or JSON - then leave off the &convert=1.
If the file is delimited other than "," then add &split= eg &split=|
You will then get XML back with each column represented as XML field - column1, column2 etc