i am studying tables in joomdoc, may i know what is these two table _joomdoc_field and _joomdoc_option used for ?

I am trying to migrate many documents from other electronic document management system to JoomDOC. Is there any way to bulk upload or import documents to new JoomDOC ? like direct add files to file folder and metadata to JoomDOC internal MySQL tables ? I can do this using programming or script or tools.